WorldWideScience

Sample records for hot melt extrusion

  1. Hot melt extrusion versus spray drying: hot melt extrusion degrades albendazole.

    Science.gov (United States)

    Hengsawas Surasarang, Soraya; Keen, Justin M; Huang, Siyuan; Zhang, Feng; McGinity, James W; Williams, Robert O

    2017-05-01

    The purpose of this study was to enhance the dissolution properties of albendazole (ABZ) by the use of amorphous solid dispersions. Phase diagrams of ABZ-polymer binary mixtures generated from Flory-Huggins theory were used to assess miscibility and processability. Forced degradation studies showed that ABZ degraded upon exposure to hydrogen peroxide and 1 N NaOH at 80 °C for 5 min, and the degradants were albendazole sulfoxide (ABZSX), and ABZ impurity A, respectively. ABZ was chemically stable following exposure to 1 N HCl at 80 °C for one hour. Thermal degradation profiles show that ABZ, with and without Kollidon ® VA 64, degraded at 180 °C and 140 °C, respectively, which indicated that ABZ could likely be processed by thermal processing. Following hot melt extrusion, ABZ degraded up to 97.4%, while the amorphous ABZ solid dispersion was successfully prepared by spray drying. Spray-dried ABZ formulations using various types of acids (methanesulfonic acid, sulfuric acid and hydrochloric acid) and polymers (Kollidon ® VA 64, Soluplus ® and Eudragit ® E PO) were studied. The spray-dried ABZ with methanesulfonic acid and Kollidon ® VA 64 substantially improved non-sink dissolution in acidic media as compared to bulk ABZ (8-fold), physical mixture of ABZ:Kollidon ® VA 64 (5.6-fold) and ABZ mesylate salt (1.6-fold). No degradation was observed in the spray-dried product for up to six months and less than 5% after one-year storage. In conclusion, amorphous ABZ solid dispersions in combination with an acid and polymer can be prepared by spray drying to enhance dissolution and shelf-stability, whereas those made by melt extrusion are degraded.

  2. Residence time modeling of hot melt extrusion processes.

    Science.gov (United States)

    Reitz, Elena; Podhaisky, Helmut; Ely, David; Thommes, Markus

    2013-11-01

    The hot melt extrusion process is a widespread technique to mix viscous melts. The residence time of material in the process frequently determines the product properties. An experimental setup and a corresponding mathematical model were developed to evaluate residence time and residence time distribution in twin screw extrusion processes. The extrusion process was modeled as the convolution of a mass transport process described by a Gaussian probability function, and a mixing process represented by an exponential function. The residence time of the extrusion process was determined by introducing a tracer at the extruder inlet and measuring the tracer concentration at the die. These concentrations were fitted to the residence time model, and an adequate correlation was found. Different parameters were derived to characterize the extrusion process including the dead time, the apparent mixing volume, and a transport related axial mixing. A 2(3) design of experiments was performed to evaluate the effect of powder feed rate, screw speed, and melt viscosity of the material on the residence time. All three parameters affect the residence time of material in the extruder. In conclusion, a residence time model was developed to interpret experimental data and to get insights into the hot melt extrusion process. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Hot-melt extrusion of sugar-starch-pellets.

    Science.gov (United States)

    Yeung, Chi-Wah; Rein, Hubert

    2015-09-30

    Sugar-starch-pellets (syn. sugar spheres) are usually manufactured through fluidized bed granulation or wet extrusion techniques. This paper introduces hot-melt extrusion (HME) as an alternative method to manufacture sugar-starch-pellets. A twin-screw extruder coupled with a Leistritz Micro Pelletizer (LMP) cutting machine was utilized for the extrusion of different types (normal-, waxy-, and high-amlyose) of corn starch, blended with varying amounts of sucrose. Pellets were characterized for their physicochemical properties including crystallinity, particle size distribution, tensile strength, and swelling expansion. Furthermore, the influence of sugar content and humidity on the product was investigated. Both sucrose and water lowered the Tg of the starch system allowing a convenient extrusion process. Mechanical strength and swelling behavior could be associated with varying amylose and amylopectin. X-ray powder diffractometric (XRPD) peaks of increasing sucrose contents appeared above 30%. This signified the oversaturation of the extruded starch matrix system with sucrose. Otherwise, had the dissolved sucrose been embedded into the molten starch matrix, no crystalline peak could have been recognized. The replacement of starch with sucrose reduced the starch pellets' swelling effect, which resulted in less sectional expansion (SEI) and changed the surface appearance. Further, a nearly equal tensile strength could be detected for sugar spheres with more than 40% sucrose. This observation stands in good relation with the analyzed values of the commercial pellets. Both techniques (fluidized bed and HME) allowed a high yield of spherical pellets (less friability) for further layering processes. Thermal influence on the sugar-starch system is still an obstacle to be controlled. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Bioavailability enhancement of atovaquone using hot melt extrusion technology.

    Science.gov (United States)

    Kate, Laxman; Gokarna, Vinod; Borhade, Vivek; Prabhu, Priyanka; Deshpande, Vinita; Pathak, Sulabha; Sharma, Shobhona; Patravale, Vandana

    2016-04-30

    Emerging parasite resistance and poor oral bioavailability of anti-malarials are the two cardinal issues which hinder the clinical success of malaria chemotherapy. Atovaquone-Proguanil is a WHO approved fixed dose combination used to tackle the problem of emerging resistance. However, Atovaquone is a highly lipophilic drug having poor aqueous solubility (less than 0.2 μg/ml) thus reducing its oral bioavailability. The aim of the present investigation was to explore hot melt extrusion (HME) as a solvent-free technique to enhance solubility and oral bioavailability of Atovaquone and to develop an oral dosage form for Atovaquone-Proguanil combination. Solid dispersion of Atovaquone was successfully developed using HME. The solid dispersion was characterized for DSC, FTIR, XRD, SEM, and flow properties. It was filled in size 2 hard gelatin capsules. The formulation showed better release as compared to Malarone® tablets, and 3.2-fold and 4.6-fold higher bioavailability as compared to Malarone® tablets and Atovaquone respectively. The enhanced bioavailability also resulted in 100% anti-malarial activity in murine infection model at 1/8(th) therapeutic dose. Thus the developed methodology shows promising potential to solve the problems associated with Atovaquone therapy, namely its high cost and poor oral bioavailability, resulting in increased therapeutic efficacy of Atovaquone. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Hot-melt extrusion for enhanced delivery of drug particles.

    Science.gov (United States)

    Miller, Dave A; McConville, Jason T; Yang, Wei; Williams, Robert O; McGinity, James W

    2007-02-01

    With the recent advent of nanotechnology for pharmaceutical applications, drug particle engineering is the focus of increasing interest as a viable approach for overcoming solubility limitations of poorly water-soluble drugs. Although these particle engineering techniques have been proven successful for enhancing the dissolution properties of many poorly water-soluble drugs, there are limitations associated with them such as particle aggregation, morphological instability, and poor wettability. The aim of this study was to demonstrate a processing technique in which hot-melt extrusion (HME) is utilized to overcome these limitations. Micronized particles of amorphous itraconazole (ITZ) stabilized with PVP or HPMC were produced and subsequently melt extruded with poloxamer 407 and PEO 200 M to deaggregate and disperse the particles into the hydrophilic polymer matrix. Differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy were used to demonstrate that the HME process did not alter the properties of the micronized particles. Dissolution testing conducted at sink conditions revealed that the dissolution rate of the micronized particles was improved by HME due to particle deaggregation and enhanced wetting. Supersaturation dissolution testing demonstrated that the ITZ-HPMC micronized particle extrudates provided superior supersaturation of ITZ compared to the ITZ-PVP micronized particle extrudates. Supersaturation dissolution testing incorporating a pH change (from pH 1.2 to 6.8 at 2 h) revealed that neither micronized particle extrudate formulation significantly reduced the rate of ITZ precipitation from supersaturated solution once pH was increased. Moreover, the two extrudate formulations performed very similarly when only considering dissolution testing from just before pH adjustment through the duration of testing at neutral pH. From oral dosing of rats, it was determined that the two extrudate formulations performed similarly in

  6. Development of poloxamer gel formulations via hot-melt extrusion technology.

    Science.gov (United States)

    Mendonsa, Nicole S; Murthy, S Narasimha; Hashemnejad, Seyed Meysam; Kundu, Santanu; Zhang, Feng; Repka, Michael A

    2018-02-15

    Poloxamer gels are conventionally prepared by the "hot" or the "cold" process. But these techniques have some disadvantages such as high energy consumption, requires expensive equipment and often have scale up issues. Therefore, the objective of this work was to develop poloxamer gels by hot-melt extrusion technology. The model drug selected was ketoprofen. The formulations developed were 30% and 40% poloxamer gels. Of these formulations, the 30% poloxamer gels were selected as ideal gels. DSC and XRD studies showed an amorphous nature of the drug after extrusion. It was observed from the permeation studies that with increasing poloxamer concentration, a decrease in drug permeation was obtained. Other studies conducted for the formulations included in-vitro release studies, texture analysis, rheological studies and pH measurements. In conclusion, the hot-melt extrusion technology could be successfully employed to develop poloxamer gels by overcoming the drawbacks associated with the conventional techniques. Published by Elsevier B.V.

  7. Oscillatory Shear Rheology in Examining the Drug-Polymer Interactions Relevant in Hot Melt Extrusion

    DEFF Research Database (Denmark)

    Aho, Johanna; Edinger, Magnus; Botker, Johan

    2016-01-01

    The flow properties of drug-polymer mixtures have a significant influence on their processability when using techniques such as hot melt extrusion (HME). Suitable extrusion temperature and screw speed to be used in laboratory scale HME were evaluated for mixtures containing 30% of paracetamol (PRC...... of the drug substances. Consecutively, the mixtures were extruded, and the maximum plasticizing weight fraction of each drug was determined by means of rheological measurements. IBU was found to have an efficient plasticizing functionality, decreasing the viscosity of the mixtures even above its apparent...

  8. Hot Melt Extrusion and Spray Drying of Co-amorphous Indomethacin-Arginine With Polymers.

    Science.gov (United States)

    Lenz, Elisabeth; Löbmann, Korbinian; Rades, Thomas; Knop, Klaus; Kleinebudde, Peter

    2017-01-01

    Co-amorphous drug-amino acid systems have gained growing interest as an alternative to common amorphous formulations which contain polymers as stabilizers. Several preparation methods have recently been investigated, including vibrational ball milling on a laboratory scale or spray drying in a larger scale. In this study, the feasibility of hot melt extrusion for continuous manufacturing of co-amorphous drug-amino acid formulations was examined, challenging the fact that amino acids melt with degradation at high temperatures. Furthermore, the need for an addition of a polymer in this process was evaluated. After a polymer screening via the solvent evaporation method, co-amorphous indomethacin-arginine was prepared by a melting-solvent extrusion process without and with copovidone. The obtained products were characterized with respect to their solid-state properties, non-sink dissolution behavior, and stability. Results were compared to those of spray-dried formulations with the same compositions and to spray-dried indomethacin-copovidone. Overall, stable co-amorphous systems could be prepared by extrusion without or with copovidone, which exhibited comparable molecular interaction properties to the respective spray-dried products, while phase separation was detected by differential scanning calorimetry in several cases. The formulations containing indomethacin in combination with arginine and copovidone showed enhanced dissolution behavior over the formulations with only copovidone or arginine. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  9. Hot-Melt Extrusion: from Theory to Application in Pharmaceutical Formulation.

    Science.gov (United States)

    Patil, Hemlata; Tiwari, Roshan V; Repka, Michael A

    2016-02-01

    Hot-melt extrusion (HME) is a promising technology for the production of new chemical entities in the developmental pipeline and for improving products already on the market. In drug discovery and development, industry estimates that more than 50% of active pharmaceutical ingredients currently used belong to the biopharmaceutical classification system II (BCS class II), which are characterized as poorly water-soluble compounds and result in formulations with low bioavailability. Therefore, there is a critical need for the pharmaceutical industry to develop formulations that will enhance the solubility and ultimately the bioavailability of these compounds. HME technology also offers an opportunity to earn intellectual property, which is evident from an increasing number of patents and publications that have included it as a novel pharmaceutical formulation technology over the past decades. This review had a threefold objective. First, it sought to provide an overview of HME principles and present detailed engineered extrusion equipment designs. Second, it included a number of published reports on the application of HME techniques that covered the fields of solid dispersions, microencapsulation, taste masking, targeted drug delivery systems, sustained release, films, nanotechnology, floating drug delivery systems, implants, and continuous manufacturing using the wet granulation process. Lastly, this review discussed the importance of using the quality by design approach in drug development, evaluated the process analytical technology used in pharmaceutical HME monitoring and control, discussed techniques used in HME, and emphasized the potential for monitoring and controlling hot-melt technology.

  10. Inline UV/Vis spectroscopy as PAT tool for hot-melt extrusion.

    Science.gov (United States)

    Wesholowski, Jens; Prill, Sebastian; Berghaus, Andreas; Thommes, Markus

    2018-01-11

    Hot-melt extrusion on co-rotating twin screw extruders is a focused technology for the production of pharmaceuticals in the context of Quality by Design. Since it is a continuous process, the potential for minimizing product quality fluctuation is enhanced. A typical application of hot-melt extrusion is the production of solid dispersions, where an active pharmaceutical ingredient (API) is distributed within a polymer matrix carrier. For this dosage form, the product quality is related amongst others to the drug content. This can be monitored on- or inline as critical quality attribute by a process analytical technology (PAT) in order to meet the specific requirements of Quality by Design. In this study, an inline UV/Vis spectrometer from ColVisTec was implemented in an early development twin screw extruder and the performance tested in accordance to the ICH Q2 guideline. Therefore, two API (carbamazepine and theophylline) and one polymer matrix (copovidone) were considered with the main focus on the quantification of the drug load. The obtained results revealed the suitability of the implemented PAT tool to quantify the drug load in a typical range for pharmaceutical applications. The effort for data evaluation was minimal due to univariate data analysis, and in combination with a measurement frequency of 1 Hz, the system is sufficient for real-time data acquisition.

  11. Hot-melt extrusion microencapsulation of quercetin for taste-masking.

    Science.gov (United States)

    Khor, Chia Miang; Ng, Wai Kiong; Kanaujia, Parijat; Chan, Kok Ping; Dong, Yuancai

    2017-02-01

    Besides its poor dissolution rate, the bitterness of quercetin also poses a challenge for further development. Using carnauba wax, shellac or zein as the shell-forming excipient, this work aimed to microencapsulate quercetin by hot-melt extrusion for taste-masking. In comparison with non-encapsulated quercetin, the microencapsulated powders exhibited significantly reduced dissolution in the simulated salivary pH 6.8 medium indicative of their potentially good taste-masking efficiency in the order of zein > carnauba wax > shellac. In vitro bitterness analysis by electronic tongue confirmed the good taste-masking efficiency of the microencapsulated powders. In vitro digestion results showed that carnauba wax and shellac-microencapsulated powders presented comparable dissolution rate with the pure quercetin in pH 1.0 (gastric) and 6.8 (intestine) medium; while zein-microencapsulated powders exhibited a remarkably slower dissolution rate. Crystallinity of quercetin was slightly reduced after microencapsulation while its chemical structure remained unchanged. Hot-melt extrusion microencapsulation could thus be an attractive technique to produce taste-masked bioactive powders.

  12. Inline monitoring and a PAT strategy for pharmaceutical hot melt extrusion.

    Science.gov (United States)

    Wahl, Patrick R; Treffer, Daniel; Mohr, Stefan; Roblegg, Eva; Koscher, Gerold; Khinast, Johannes G

    2013-10-15

    Implementation of continuous manufacturing in the pharmaceutical industry requires tight process control. This study focuses on a PAT strategy for hot melt extrusion of vegetable calcium stearate (CaSt) as matrix carrier and paracetamol as active pharmaceutical ingredient (API). The extrusion was monitored using in-line near-infrared (NIR) spectroscopy. A NIR probe was located in the section between the extrusion screws and the die, using a novel design of the die channel. A chemometric model was developed based on premixes at defined concentrations and was implemented in SIPAT for real time API concentration monitoring. Subsequently, step experiments were performed for different API concentrations, screw speeds and screw designs. The predicted API concentration was in good agreement with the pre-set concentrations. The transition from one API plateau to another was a smooth curve due to the mixing behaviour of the extruder. The accuracy of the model was confirmed via offline HPLC analysis. The screw design was determined as the main influential factor on content uniformity (CU). Additionally the influence of multiple feeders had a significant impact on CU. The results demonstrate that in-line NIR measurements is a powerful tool for process development (e.g., mixing characterization), monitoring and further control strategies. Copyright © 2013. Published by Elsevier B.V.

  13. A Miniaturized Extruder to Prototype Amorphous Solid Dispersions: Selection of Plasticizers for Hot Melt Extrusion.

    Science.gov (United States)

    Lauer, Matthias E; Maurer, Reto; Paepe, Anne T De; Stillhart, Cordula; Jacob, Laurence; James, Rajesh; Kojima, Yuki; Rietmann, Rene; Kissling, Tom; van den Ende, Joost A; Schwarz, Sabine; Grassmann, Olaf; Page, Susanne

    2018-05-19

    Hot-melt extrusion is an option to fabricate amorphous solid dispersions and to enhance oral bioavailability of poorly soluble compounds. The selection of suitable polymer carriers and processing aids determines the dissolution, homogeneity and stability performance of this solid dosage form. A miniaturized extrusion device (MinEx) was developed and Hypromellose acetate succinate type L (HPMCAS-L) based extrudates containing the model drugs neurokinin-1 (NK1) and cholesterylester transfer protein (CETP) were manufactured, plasticizers were added and their impact on dissolution and solid-state properties were assessed. Similar mixtures were manufactured with a lab-scale extruder, for face to face comparison. The properties of MinEx extrudates widely translated to those manufactured with a lab-scale extruder. Plasticizers, Polyethyleneglycol 4000 (PEG4000) and Poloxamer 188, were homogenously distributed but decreased the storage stability of the extrudates. Stearic acid was found condensed in ultrathin nanoplatelets which did not impact the storage stability of the system. Depending on their distribution and physicochemical properties, plasticizers can modulate storage stability and dissolution performance of extrudates. MinEx is a valuable prototyping-screening method and enables rational selection of plasticizers in a time and material sparing manner. In eight out of eight cases the properties of the extrudates translated to products manufactured in lab-scale extrusion trials.

  14. Numerical simulation of hot-melt extrusion processes for amorphous solid dispersions using model-based melt viscosity.

    Science.gov (United States)

    Bochmann, Esther S; Steffens, Kristina E; Gryczke, Andreas; Wagner, Karl G

    2018-03-01

    Simulation of HME processes is a valuable tool for increased process understanding and ease of scale-up. However, the experimental determination of all required input parameters is tedious, namely the melt rheology of the amorphous solid dispersion (ASD) in question. Hence, a procedure to simplify the application of hot-melt extrusion (HME) simulation for forming amorphous solid dispersions (ASD) is presented. The commercial 1D simulation software Ludovic ® was used to conduct (i) simulations using a full experimental data set of all input variables including melt rheology and (ii) simulations using model-based melt viscosity data based on the ASDs glass transition and the physical properties of polymeric matrix only. Both types of HME computation were further compared to experimental HME results. Variation in physical properties (e.g. heat capacity, density) and several process characteristics of HME (residence time distribution, energy consumption) among the simulations and experiments were evaluated. The model-based melt viscosity was calculated by using the glass transition temperature (T g ) of the investigated blend and the melt viscosity of the polymeric matrix by means of a T g -viscosity correlation. The results of measured melt viscosity and model-based melt viscosity were similar with only few exceptions, leading to similar HME simulation outcomes. At the end, the experimental effort prior to HME simulation could be minimized and the procedure enables a good starting point for rational development of ASDs by means of HME. As model excipients, Vinylpyrrolidone-vinyl acetate copolymer (COP) in combination with various APIs (carbamazepine, dipyridamole, indomethacin, and ibuprofen) or polyethylene glycol (PEG 1500) as plasticizer were used to form the ASDs. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Polymorphic Transformation of Indomethacin during Hot Melt Extrusion Granulation: Process and Dissolution Control.

    Science.gov (United States)

    Xu, Ting; Nahar, Kajalajit; Dave, Rutesh; Bates, Simon; Morris, Kenneth

    2018-05-10

    To study and elucidate the effect of the intensity and duration of processing stresses on the possible solid-state changes during a hot melt extrusion granulation process. Blends of α-indomethacin and PEG 3350 (w/w 4:1) were granulated using various screw sizes/designs on the melt extruder under different temperature regimes. Differential Scanning Calorimetry and X-ray Powder Diffraction were employed for characterization. The dissolution behavior of the pure polymorphs and the resulting granules was determined using in-situ fiber optic UV testing system. An XRPD quantitation method using Excel full pattern fitting was developed to determine the concentration of each constituent (amorphous, α and γ indomethacin and PEG) in samples collected from each functioning zone and in granules. Analysis of in-process samples and granules revealed that higher temperature (≥130°C) and shear stress accelerated the process induced phase transitions from amorphous and/or the α form to γ indomethacin during heating stage. However, rapid cooling resulted in an increased percentage of the α form allowing isolation of the meta-stable form. By determining the conditions that either prevent or facilitate process induced transformations of IMC polymorphs during melt granulation, a design space was developed to control the polymorph present in the resulting granules. This represents the conditions necessary to balance the thermodynamic relationships between the polymorphs of the IMC system and the kinetics of the possible transformations as a function of the processing stresses.

  16. Coupling 3D printing with hot-melt extrusion to produce controlled-release tablets.

    Science.gov (United States)

    Zhang, Jiaxiang; Feng, Xin; Patil, Hemlata; Tiwari, Roshan V; Repka, Michael A

    2017-03-15

    The main objective of this work was to explore the potential of coupling fused deposition modeling in three-dimensional (3D) printing with hot-melt extrusion (HME) technology to facilitate additive manufacturing, in order to fabricate tablets with enhanced extended release properties. Acetaminophen was used as the model drug and different grades and ratios of polymers were used to formulate tablets. Three-point bending and hardness tests were performed to determine the mechanical properties of the filaments and tablets. 3D-printed tablets, directly compressed mill-extruded tablets, and tablets prepared from a physical mixture were evaluated for drug release rates using a USP-II dissolution apparatus. The surface and cross-sectional morphology of the 3D-printed tablets were assessed by scanning electron microscopy. Differential scanning calorimetry and thermogravimetric analysis were used to characterize the crystal states and thermal properties of materials, respectively. The 3D-printed tablets had smooth surfaces and tight structures; therefore, they showed better extended drug release rates than the directly compressed tablets did. Further, this study clearly demonstrated the feasibility of coupling HME with 3D printing technology, which allows for the formulation of drug delivery systems using different grades and ratios of pharmaceutical polymers. In addition, formulations can be made based on the personal needs of patients. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. A novel hot-melt extrusion formulation of albendazole for increasing dissolution properties.

    Science.gov (United States)

    Martinez-Marcos, Laura; Lamprou, Dimitrios A; McBurney, Roy T; Halbert, Gavin W

    2016-02-29

    The main aim of the research focused on the production of hot-melt extrusion (HME) formulations with increased dissolution properties of albendazole (ABZ). Therefore, HME was applied as a continuous manufacturing technique to produce amorphous solid dispersions of the poorly water soluble drug ABZ combined with the polymer matrix polyvinylpyrrolidone PVP K12. HME formulations of ABZ-PVP K12 comprised a drug content of 1%, 5% and 10% w/w. The main analytical characterisation techniques used were scanning electron microscopy (SEM), micro-computed tomography (μ-CT), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and dissolution profile studies. The application of SEM, XRPD and DSC evidenced drug physical transformation from crystalline to amorphous state and therefore, the achievement of an amorphous solid dispersion. The introduction of a novel technique, μ-CT, to characterise the internal structure of these materials revealed key information regarding materials distribution and void content. Dissolution profile studies evidenced a high increase in drug release profile compared to pure ABZ. These promising results can lead to a great enhancement of the oral bioavailability of ABZ dosage forms. Therefore, HME is a potential continuous manufacturing technique to overcome ABZ poor solubility properties and lead to a significant increase in the therapeutic effect. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. FDM 3D printing of modified drug-delivery systems using hot melt extrusion: a new approach for individualized therapy.

    Science.gov (United States)

    Cunha-Filho, Marcilio; Araújo, Maísa Rp; Gelfuso, Guilherme M; Gratieri, Tais

    2017-11-01

    The production process of 3D-printed drugs offers unique advantages such as the possibility of individualizing the drug therapy and easily associating different drugs and release technologies in the same pharmaceutical unit. Fused deposition modeling, a 3D printing technique, seems especially interesting for pharmaceutical applications, due to its low cost, precise and reproducible control of the printed structures, and versatility for industrial and laboratory scale. This technique combined with another technology already adapted for the pharmaceutical industry, the hot melt extrusion, is able to incorporate various mechanisms of modified drug release. This special report aims to bring together data of the experimental progress achieved using the fused deposition modeling 3D printing combined with hot melt extrusion technique and its potential in drug delivery. [Formula: see text].

  19. Hot Melt Extrusion as Solvent-Free Technique for a Continuous Manufacturing of Drug-Loaded Mesoporous Silica

    DEFF Research Database (Denmark)

    Genina, Natalja; Hadi, Batol; Löbmann, Korbinian

    2018-01-01

    The aim of this study is to explore hot melt extrusion (HME) as a solvent-free drug loading technique for preparation of stable amorphous solid dispersions using mesoporous silica (PSi). Ibuprofen and carvedilol were used as poorly soluble active pharmaceutical ingredients (APIs). Due to the high...... friction of an API:PSi mixture below the loading limit of the API, it was necessary to add the polymer Soluplus(®) (SOL) in order to enable the extrusion process. As a result, the APIs were distributed between the PSi and SOL phase after HME. Due to its higher affinity to PSi, ibuprofen was mainly adsorbed...... into the PSi, whereas carvedilol was mainly found in the SOL phase. Intrinsic dissolution rate was highest for HME formulations, containing PSi, compared to pure crystalline (amorphous) APIs and HME formulations without PSi. HME is a feasible solvent-free drug loading technique for preparation of PSi...

  20. Investigation of Thermal and Viscoelastic Properties of Polymers Relevant to Hot Melt Extrusion, IV: Affinisol™ HPMC HME Polymers.

    Science.gov (United States)

    Gupta, Simerdeep Singh; Solanki, Nayan; Serajuddin, Abu T M

    2016-02-01

    Most cellulosic polymers cannot be used as carriers for preparing solid dispersion of drugs by hot melt extrusion (HME) due to their high melt viscosity and thermal degradation at high processing temperatures. Three HME-grade hydroxypropyl methylcelluloses, namely Affinisol™ HPMC HME 15 cP, Affinisol™ HPMC HME 100 cP, and Affinisol™ HPMC HME 4 M, have recently been introduced by The Dow Chemical Co. to enable the preparation of solid dispersion at lower and more acceptable processing temperatures. In the present investigation, physicochemical properties of the new polymers relevant to HME were determined and compared with that of Kollidon(®) VA 64. Powder X-ray diffraction (PXRD), modulated differential scanning calorimetry (mDSC), thermogravimetric analysis (TGA), moisture sorption, rheology, and torque analysis by melt extrusion were applied. PXRD and mDSC showed that the Affinisol™ polymers were amorphous in nature. According to TGA, the onset of degradation for all polymers was >220°C. The Affinisol™ polymers exhibited less hygroscopicity than Kollidon(®) VA 64 and another HPMC polymer, Methocel™ K100LV. The complex viscosity profiles of the Affinisol™ polymers as a function of temperature were similar. The viscosity of the Affinisol™ polymers was highly sensitive to the shear rate applied, and unlike Kollidon(®) VA 64, the viscosity decreased drastically when the angular frequency was increased. Because of the very high shear rate encountered during melt extrusion, Affinisol™ polymers showed capability of being extruded at larger windows of processing temperatures as compared to that of Kollidon(®) VA 64.

  1. Oral transmucosal delivery of domperidone from immediate release films produced via hot-melt extrusion technology.

    Science.gov (United States)

    Palem, Chinna Reddy; Kumar Battu, Sunil; Maddineni, Sindhuri; Gannu, Ramesh; Repka, Michael A; Yamsani, Madhusudan Rao

    2013-02-01

    The objective of the study was to prepare and characterize the domperidone (DOM) hot-melt extruded (HME) buccal films by both in vitro and in vivo techniques. The HME film formulations contained PEO N10 and/or its combination with HPMC E5 LV or Eudragit RL100 as polymeric carriers, and PEG3350 as a plasticizer. The blends were co-processed at a screw speed of 50 rpm with the barrel temperatures ranging from 120-160°C utilizing a bench top co-rotating twin-screw hot-melt extruder using a transverse-slit die. The HME films were evaluated for drug content, drug excipient interaction, in vitro drug release, mechanical properties, in vivo residence time, in vitro bioadhesion, swelling and erosion, ex vivo permeation from HME films and the selected optimal formulation was subjected for bioavailability studies in healthy human volunteers. The extruded films demonstrated no drug excipient interaction and excellent content uniformity. The selected HME film formulation (DOM2) exhibited a tensile strength (0.72 Kg/mm(2)), elongation at break (28.4% mm(2)), in vivo residence time (120 min), peak detachment force (1.55 N), work of adhesion (1.49 mJ), swelling index (210.2%), erosion (10.5%) and in vitro drug release of 84.8% in 2 h. Bioavailability from the optimized HME buccal films was 1.5 times higher than the oral dosage form and the results showed statistically significant (p buccal-adhesive films with improved bioavailability characteristics.

  2. Rheology Guided Rational Selection of Processing Temperature To Prepare Copovidone-Nifedipine Amorphous Solid Dispersions via Hot Melt Extrusion (HME).

    Science.gov (United States)

    Yang, Fengyuan; Su, Yongchao; Zhang, Jingtao; DiNunzio, James; Leone, Anthony; Huang, Chengbin; Brown, Chad D

    2016-10-03

    The production of amorphous solid dispersions via hot melt extrusion (HME) relies on elevated temperature and prolonged residence time, which can result in potential degradation and decomposition of thermally sensitive components. Herein, the rheological properties of a physical mixture of polymer and an active pharmaceutical ingredient (API) were utilized to guide the selection of appropriate HME processing temperature. In the currently studied copovidone-nifedipine system, a critical temperature, which is substantially lower (∼13 °C) than the melting point of crystalline API, was captured during a temperature ramp examination and regarded as the critical point at which the API could molecularly dissolve into the polymer. Based on the identification of this critical point, various solid dispersions were prepared by HME processing below, at, and above the critical temperature (both below and above the melting temperature (T m ) of crystalline API). In addition, the resultant extrudates along with two control solid dispersions prepared by physical mixing and cryogenic milling were assessed by X-ray diffraction, differential scanning calorimetry, hot stage microscopy, rheology, and solid-state NMR. Physicochemical properties of resultant solid dispersions indicated that the identified critical temperature is sufficient for the polymer-API system to reach a molecular-level mixing, manifested by the transparent and smooth appearance of extrudates, the absence of API crystalline diffraction and melting peaks, dramatically decreased rheological properties, and significantly improved polymer-API miscibility. Once the critical temperature has been achieved, further raising the processing temperature only results in limited improvement of API dispersion, reflected by slightly reduced storage modulus and complex viscosity and limited improvement in miscibility.

  3. Process design and control of a twin screw hot melt extrusion for continuous pharmaceutical tamper-resistant tablet production.

    Science.gov (United States)

    Baronsky-Probst, J; Möltgen, C-V; Kessler, W; Kessler, R W

    2016-05-25

    Hot melt extrusion (HME) is a well-known process within the plastic and food industries that has been utilized for the past several decades and is increasingly accepted by the pharmaceutical industry for continuous manufacturing. For tamper-resistant formulations of e.g. opioids, HME is the most efficient production technique. The focus of this study is thus to evaluate the manufacturability of the HME process for tamper-resistant formulations. Parameters such as the specific mechanical energy (SME), as well as the melt pressure and its standard deviation, are important and will be discussed in this study. In the first step, the existing process data are analyzed by means of multivariate data analysis. Key critical process parameters such as feed rate, screw speed, and the concentration of the API in the polymers are identified, and critical quality parameters of the tablet are defined. In the second step, a relationship between the critical material, product and process quality attributes are established by means of Design of Experiments (DoEs). The resulting SME and the temperature at the die are essential data points needed to indirectly qualify the degradation of the API, which should be minimal. NIR-spectroscopy is used to monitor the material during the extrusion process. In contrast to most applications in which the probe is directly integrated into the die, the optical sensor is integrated into the cooling line of the strands. This saves costs in the probe design and maintenance and increases the robustness of the chemometric models. Finally, a process measurement system is installed to monitor and control all of the critical attributes in real-time by means of first principles, DoE models, soft sensor models, and spectroscopic information. Overall, the process is very robust as long as the screw speed is kept low. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. A comparative study between hot-melt extrusion and spray-drying for the manufacture of anti-hypertension compatible monolithic fixed-dose combination products.

    Science.gov (United States)

    Kelleher, J F; Gilvary, G C; Madi, A M; Jones, D S; Li, S; Tian, Y; Almajaan, A; Senta-Loys, Z; Andrews, G P; Healy, A M

    2018-07-10

    The purpose of this work was to investigate the application of different advanced continuous processing techniques (hot melt extrusion and spray drying) to the production of fixed-dose combination (FDC) monolithic systems comprising of hydrochlorothiazide and ramipril for the treatment of hypertension. Identical FDC formulations were manufactured by the two different methods and were characterised using powder X-ray diffraction (PXRD) and modulated differential scanning calorimetry (mDSC). Drug dissolution rates were investigated using a Wood's apparatus, while physical stability was assessed on storage under controlled temperature and humidity conditions. Interestingly both drugs were transformed into their amorphous forms when spray dried, however, hydrochlorothiazide was determined, by PXRD, to be partially crystalline when hot melt extruded with either polymer carrier (Kollidon® VA 64 or Soluplus®). Hot melt extrusion was found to result in significant degradation of ramipril, however, this could be mitigated by the inclusion of the plasticizer, polyethylene glycol 3350, in the formulation and appropriate adjustment of processing temperature. The results of intrinsic dissolution rate studies showed that hot-melt extruded samples were found to release both drugs faster than identical formulations produced via spray drying. However, the differences were attributable to the surface roughness of the compressed discs in the Wood's apparatus, rather than solid state differences between samples. After a 60-day stability study spray dried samples exhibited a greater physical stability than the equivalent hot melt extruded samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. A New Method of Constructing a Drug-Polymer Temperature-Composition Phase Diagram Using Hot-Melt Extrusion.

    Science.gov (United States)

    Tian, Yiwei; Jones, David S; Donnelly, Conor; Brannigan, Timothy; Li, Shu; Andrews, Gavin P

    2018-04-02

    Current experimental methodologies used to determine the thermodynamic solubility of an API within a polymer typically involves establishing the dissolution/melting end point of the crystalline API within a physical mixture or through the use of the glass transition temperature measurement of a demixed amorphous solid dispersion. The measurable "equilibrium" points for solubility are normally well above the glass transition temperature of the system, meaning extrapolation is required to predict the drug solubility at pharmaceutically relevant temperatures. In this manuscript, we argue that the presence of highly viscous polymers in these systems results in experimental data that exhibits an under or overestimated value relative to the true thermodynamic solubility. In previous work, we demonstrated the effects of experimental conditions and their impact on measured and predicted thermodynamic solubility points. In light of current understanding, we have developed a new method to limit error associated with viscosity effects for application in small-scale hot-melt extrusion (HME). In this study, HME was used to generate an intermediate (multiphase) system containing crystalline drug, amorphous drug/polymer-rich regions as well as drug that was molecularly dispersed in polymer. An extended annealing method was used together with high-speed differential scanning calorimetry to accurately determine the upper and lower boundaries of the thermodynamic solubility of a model drug-polymer system (felodipine and Soluplus). Compared to our previously published data, the current results confirmed our hypothesis that the prediction of the liquid-solid curve using dynamic determination of dissolution/melting end point of the crystalline API physical mixture presents an underestimation relative to the thermodynamic solubility point. With this proposed method, we were able to experimentally measure the upper and lower boundaries of the liquid-solid curve for the model system. The

  6. Creating Drug Solubilization Compartments via Phase Separation in Multicomponent Buccal Patches Prepared by Direct Hot Melt Extrusion-Injection Molding.

    Science.gov (United States)

    Alhijjaj, Muqdad; Bouman, Jacob; Wellner, Nikolaus; Belton, Peter; Qi, Sheng

    2015-12-07

    Creating in situ phase separation in solid dispersion based formulations to allow enhanced functionality of the dosage form, such as improving dissolution of poorly soluble model drug as well as being mucoadhesive, can significantly maximize the in vitro and in vivo performance of the dosage form. This formulation strategy can benefit a wide range of solid dosage forms for oral and alternative routes of delivery. This study using buccal patches as an example created separated phases in situ of the buccal patches by selecting the excipients with different miscibility with each other and the model drug. The quaternary dispersion based buccal patches containing PEG, PEO, Tween 80, and felodipine were prepared by direct hot melt extrusion-injection molding (HME-IM). The partial miscibility between Tween 80 and semicrystalline PEG-PEO led to the phase separation after extrusion. The Tween phases acted as drug solubilization compartments, and the PEG-PEO phase had the primary function of providing mucoadhesion and carrier controlled dissolution. As felodipine was preferably solubilized in the amorphous regions of PEG-PEO, the high crystallinity of PEG-PEO resulted in an overall low drug solubilizing capacity. Tween 80 was added to improve the solubilization capacity of the system as the model drug showed good solubility in Tween. Increasing the drug loading led to the supersaturation of drug in Tween compartments and crystalline drug dispersed in PEG-PEO phases. The spatial distribution of these phase-separated compartments was mapped using X-ray micro-CT, which revealed that the domain size and heterogeneity of the phase separation increased with increasing the drug loading. The outcome of this study provides new insights into the applicability of in situ formed phase separation as a formulation strategy for the delivery of poorly soluble drugs and demonstrated the basic principle of excipient selection for such technology.

  7. Mechanical properties and drug release of venlafaxine HCl solid mini matrices prepared by hot-melt extrusion and hot or ambient compression.

    Science.gov (United States)

    Avgerinos, Theodoros; Kantiranis, Nikolaos; Panagopoulou, Athanasia; Malamataris, Stavros; Kachrimanis, Kyriakos; Nikolakakis, Ioannis

    2018-02-01

    Objective/significance: To elucidate the role of plasticizers in different mini matrices and correlate mechanical properties with drug release. Cylindrical pellets were prepared by hot-melt extrusion (HME) and mini tablets by hot (HC) and ambient compression (AC). Venlafaxine HCl was the model drug, Eudragit ® RSPO the matrix former and citric acid or Lutrol ® F127 the plasticizers. The matrices were characterized for morphology, crystallinity, and mechanical properties. The influence of plasticizer's type and content on the extrusion pressure (P e ) during HME and ejection during tableting was examined and the mechanical properties were correlated with drug release parameters. Resistance to extrusion and tablet ejection force were reduced by Lutrol ® F127 which also produced softer and weaker pellets with faster release, but harder and stronger HC tablets with slower release. HME pellets showed greater tensile strength (T) and 100 times slower release than tablets. P e correlated with T and resistance to deformation of the corresponding pellets (r 2  = 0.963 and 0.945). For both HME and HC matrices the decrease of drug release with T followed a single straight line (r 2  = 0.990) and for HME the diffusion coefficient (D e ) and retreat rate constant (k b ) decreased linearly with T (r 2  = 0.934 and 0.972). Lutrol ® F127 and citric acid are efficient plasticizers and Lutrol ® F127 is a thermal binder/lubricant in HC compression. The different bonding mechanisms of the matrices were reflected in the mechanical strength and drug release. Relationships established between T and drug release parameters for HME and HC matrices may be useful during formulation work.

  8. Matrix-assisted cocrystallization (MAC) simultaneous production and formulation of pharmaceutical cocrystals by hot-melt extrusion.

    Science.gov (United States)

    Boksa, Kevin; Otte, Andrew; Pinal, Rodolfo

    2014-09-01

    A novel method for the simultaneous production and formulation of pharmaceutical cocrystals, matrix-assisted cocrystallization (MAC), is presented. Hot-melt extrusion (HME) is used to create cocrystals by coprocessing the drug and coformer in the presence of a matrix material. Carbamazepine (CBZ), nicotinamide (NCT), and Soluplus were used as a model drug, coformer, and matrix, respectively. The MAC product containing 80:20 (w/w) cocrystal:matrix was characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, and powder X-ray diffraction. A partial least squares (PLS) regression model was developed for quantifying the efficiency of cocrystal formation. The MAC product was estimated to be 78% (w/w) cocrystal (theoretical 80%), with approximately 0.3% mixture of free (unreacted) CBZ and NCT, and 21.6% Soluplus (theoretical 20%) with the PLS model. A physical mixture (PM) of a reference cocrystal (RCC), prepared by precipitation from solution, and Soluplus resulted in faster dissolution relative to the pure RCC. However, the MAC product with the exact same composition resulted in considerably faster dissolution and higher maximum concentration (∼five-fold) than those of the PM. The MAC product consists of high-quality cocrystals embedded in a matrix. The processing aspect of MAC plays a major role on the faster dissolution observed. The MAC approach offers a scalable process, suitable for the continuous manufacturing and formulation of pharmaceutical cocrystals. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  9. Hot Melt Extrusion and Spray Drying of Co-amorphous Indomethacin-Arginine With Polymers

    DEFF Research Database (Denmark)

    Lenz, Elisabeth; Löbmann, Korbinian; Rades, Thomas

    2017-01-01

    Co-amorphous drug-amino acid systems have gained growing interest as an alternative to common amorphous formulations which contain polymers as stabilizers. Several preparation methods have recently been investigated, including vibrational ball milling on a laboratory scale or spray drying......, and stability. Results were compared to those of spray-dried formulations with the same compositions and to spray-dried indomethacin-copovidone. Overall, stable co-amorphous systems could be prepared by extrusion without or with copovidone, which exhibited comparable molecular interaction properties...... to the respective spray-dried products, while phase separation was detected by differential scanning calorimetry in several cases. The formulations containing indomethacin in combination with arginine and copovidone showed enhanced dissolution behavior over the formulations with only copovidone or arginine....

  10. Development of Tablet Formulation of Amorphous Solid Dispersions Prepared by Hot Melt Extrusion Using Quality by Design Approach.

    Science.gov (United States)

    Agrawal, Anjali; Dudhedia, Mayur; Deng, Weibin; Shepard, Kevin; Zhong, Li; Povilaitis, Edward; Zimny, Ewa

    2016-02-01

    The objective of the study was to identify the extragranular component requirements (level and type of excipients) to develop an immediate release tablet of solid dispersions prepared by hot melt extrusion (HME) process using commonly used HME polymers. Solid dispersions of compound X were prepared using polyvinyl pyrrolidone co-vinyl acetate 64 (PVP VA64), Soluplus, and hypromellose acetate succinate (HPMCAS-LF) polymers in 1:2 ratio by HME through 18 mm extruder. A mixture design was employed to study effect of type of polymer, filler (microcrystalline cellulose (MCC), lactose, and dicalcium phosphate anhydrous (DCPA)), and disintegrant (Crospovidone, croscarmellose sodium, and sodium starch glycolate (SSG)) as well as level of extrudates, filler, and disintegrant on tablet properties such as disintegration time (DT), tensile strength (TS), compactibility, and dissolution. Higher extrudate level resulted in longer DT and lower TS so 60-70% was the maximum amount of acceptable extrudate level in tablets. Fast disintegration was achieved with HPMCAS-containing tablets, whereas Soluplus- and PVP VA64-containing tablets had higher TS. Crospovidone and croscarmellose sodium were more suitable disintegrant than SSG to achieve short DT, and MCC was a suitable filler to prepare tablets with acceptable TS for each studied HME polymer. The influence of extragranular components on dissolution from tablets should be carefully evaluated while finalizing tablet composition, as it varies for each HME polymer. The developed statistical models identified suitable level of fillers and disintegrants for each studied HME polymer to achieve tablets with rapid DT (tablet porosity), and their predictivity was confirmed by conducting internal and external validation studies.

  11. Optimising Drug Solubilisation in Amorphous Polymer Dispersions: Rational Selection of Hot-melt Extrusion Processing Parameters.

    Science.gov (United States)

    Li, Shu; Tian, Yiwei; Jones, David S; Andrews, Gavin P

    2016-02-01

    The aim of this article was to construct a T-ϕ phase diagram for a model drug (FD) and amorphous polymer (Eudragit® EPO) and to use this information to understand the impact of how temperature-composition coordinates influenced the final properties of the extrudate. Defining process boundaries and understanding drug solubility in polymeric carriers is of utmost importance and will help in the successful manufacture of new delivery platforms for BCS class II drugs. Physically mixed felodipine (FD)-Eudragit(®) EPO (EPO) binary mixtures with pre-determined weight fractions were analysed using DSC to measure the endset of melting and glass transition temperature. Extrudates of 10 wt% FD-EPO were processed using temperatures (110°C, 126°C, 140°C and 150°C) selected from the temperature-composition (T-ϕ) phase diagrams and processing screw speed of 20, 100 and 200rpm. Extrudates were characterised using powder X-ray diffraction (PXRD), optical, polarised light and Raman microscopy. To ensure formation of a binary amorphous drug dispersion (ADD) at a specific composition, HME processing temperatures should at least be equal to, or exceed, the corresponding temperature value on the liquid-solid curve in a F-H T-ϕ phase diagram. If extruded between the spinodal and liquid-solid curve, the lack of thermodynamic forces to attain complete drug amorphisation may be compensated for through the use of an increased screw speed. Constructing F-H T-ϕ phase diagrams are valuable not only in the understanding drug-polymer miscibility behaviour but also in rationalising the selection of important processing parameters for HME to ensure miscibility of drug and polymer.

  12. Continuous production of fenofibrate solid lipid nanoparticles by hot-melt extrusion technology: a systematic study based on a quality by design approach.

    Science.gov (United States)

    Patil, Hemlata; Feng, Xin; Ye, Xingyou; Majumdar, Soumyajit; Repka, Michael A

    2015-01-01

    This contribution describes a continuous process for the production of solid lipid nanoparticles (SLN) as drug-carrier systems via hot-melt extrusion (HME). Presently, HME technology has not been used for the manufacturing of SLN. Generally, SLN are prepared as a batch process, which is time consuming and may result in variability of end-product quality attributes. In this study, using Quality by Design (QbD) principles, we were able to achieve continuous production of SLN by combining two processes: HME technology for melt-emulsification and high-pressure homogenization (HPH) for size reduction. Fenofibrate (FBT), a poorly water-soluble model drug, was incorporated into SLN using HME-HPH methods. The developed novel platform demonstrated better process control and size reduction compared to the conventional process of hot homogenization (batch process). Varying the process parameters enabled the production of SLN below 200 nm. The dissolution profile of the FBT SLN prepared by the novel HME-HPH method was faster than that of the crude FBT and a micronized marketed FBT formulation. At the end of a 5-h in vitro dissolution study, a SLN formulation released 92-93% of drug, whereas drug release was approximately 65 and 45% for the marketed micronized formulation and crude drug, respectively. Also, pharmacokinetic study results demonstrated a statistical increase in Cmax, Tmax, and AUC0-24 h in the rate of drug absorption from SLN formulations as compared to the crude drug and marketed micronized formulation. In summary, the present study demonstrated the potential use of hot-melt extrusion technology for continuous and large-scale production of SLN.

  13. Development of Maltodextrin-Based Immediate-Release Tablets Using an Integrated Twin-Screw Hot-Melt Extrusion and Injection-Molding Continuous Manufacturing Process.

    Science.gov (United States)

    Puri, Vibha; Brancazio, Dave; Desai, Parind M; Jensen, Keith D; Chun, Jung-Hoon; Myerson, Allan S; Trout, Bernhardt L

    2017-11-01

    The combination of hot-melt extrusion and injection molding (HME-IM) is a promising process technology for continuous manufacturing of tablets. However, there has been limited research on its application to formulate crystalline drug-containing immediate-release tablets. Furthermore, studies that have applied the HME-IM process to molded tablets have used a noncontinuous 2-step approach. The present study develops maltodextrin (MDX)-based extrusion-molded immediate-release tablets for a crystalline drug (griseofulvin) using an integrated twin-screw HME-IM continuous process. At 10% w/w drug loading, MDX was selected as the tablet matrix former based on a preliminary screen. Furthermore, liquid and solid polyols were evaluated for melt processing of MDX and for impact on tablet performance. Smooth-surfaced tablets, comprising crystalline griseofulvin solid suspension in the amorphous MDX-xylitol matrix, were produced by a continuous process on a twin-screw extruder coupled to a horizontally opening IM machine. Real-time HME process profiles were used to develop automated HME-IM cycles. Formulation adjustments overcame process challenges and improved tablet strength. The developed MDX tablets exhibited adequate strength and a fast-dissolving matrix (85% drug release in 20 min), and maintained performance on accelerated stability conditions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  14. Application of carrier and plasticizer to improve the dissolution and bioavailability of poorly water-soluble baicalein by hot melt extrusion.

    Science.gov (United States)

    Zhang, Yilan; Luo, Rui; Chen, Yi; Ke, Xue; Hu, Danrong; Han, Miaomiao

    2014-06-01

    The objective of this study was to develop a suitable formulation for baicalein (a poorly water-soluble drug exhibiting high melting point) to prepare solid dispersions using hot melt extrusion (HME). Proper carriers and plasticizers were selected by calculating the Hansen solubility parameters, evaluating melting processing condition, and measuring the solubility of obtained melts. The characteristic of solid dispersions prepared by HME was evaluated. The dissolution performance of the extrudates was compared to the pure drug and the physical mixtures. Physicochemical properties of the extrudates were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR). Relative bioavailability after oral administration in beagle dogs was assessed. As a result, Kollidon VA64 and Eudragit EPO were selected as two carriers; Cremophor RH was used as the plasticizer. The dissolution of all the extrudates was significantly improved. DSC and PXRD results suggested that baicalein in the extrudates was amorphous. FTIR spectroscopy revealed the interaction between drug and polymers. After oral administration, the relative bioavailability of solid dispersions with VA64 and EPO was comparative, about 2.4- and 2.9-fold greater compared to the pure drug, respectively.

  15. A comparative study of the effect of spray drying and hot-melt extrusion on the properties of amorphous solid dispersions containing felodipine.

    Science.gov (United States)

    Mahmah, Osama; Tabbakh, Rami; Kelly, Adrian; Paradkar, Anant

    2014-02-01

    To compare the properties of solid dispersions of felodipine for oral bioavailability enhancement using two different polymers, polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose acetate succinate (HPMCAS), by hot-melt extrusion (HME) and spray drying. Felodipine solid dispersions were prepared by HME and spray drying techniques. PVP and HPMCAS were used as polymer matrices at different drug : polymer ratios (1 : 1, 1 : 2 and 1 : 3). Detailed characterization was performed using differential scanning calorimetry, powder X-ray diffractometry, scanning electron microscopy and in-vitro dissolution testing. Dissolution profiles were evaluated in the presence of sodium dodecyl sulphate. Stability of different solid dispersions was studied under accelerated conditions (40°C/75% RH) over 8 weeks. Spray-dried formulations were found to release felodipine faster than melt extruded formulations for both polymer matrices. Solid dispersions containing HMPCAS exhibited higher drug release rates and better wettability than those produced with a PVP matrix. No significant differences in stability were observed except with HPMCAS at a 1 : 1 ratio, where crystallization was detected in spray-dried formulations. Solid dispersions of felodipine produced by spray drying exhibited more rapid drug release than corresponding melt extruded formulations, although in some cases improved stability was observed for melt extruded formulations. © 2013 Royal Pharmaceutical Society.

  16. Development and Performance of a Highly Sensitive Model Formulation Based on Torasemide to Enhance Hot-Melt Extrusion Process Understanding and Process Development.

    Science.gov (United States)

    Evans, Rachel C; Kyeremateng, Samuel O; Asmus, Lutz; Degenhardt, Matthias; Rosenberg, Joerg; Wagner, Karl G

    2018-02-27

    The aim of this work was to investigate the use of torasemide as a highly sensitive indicator substance and to develop a formulation thereof for establishing quantitative relationships between hot-melt extrusion process conditions and critical quality attributes (CQAs). Using solid-state characterization techniques and a 10 mm lab-scale co-rotating twin-screw extruder, we studied torasemide in a Soluplus® (SOL)-polyethylene glycol 1500 (PEG 1500) matrix, and developed and characterized a formulation which was used as a process indicator to study thermal- and hydrolysis-induced degradation, as well as residual crystallinity. We found that torasemide first dissolved into the matrix and then degraded. Based on this mechanism, extrudates with measurable levels of degradation and residual crystallinity were produced, depending strongly on the main barrel and die temperature and residence time applied. In addition, we found that 10% w/w PEG 1500 as plasticizer resulted in the widest operating space with the widest range of measurable residual crystallinity and degradant levels. Torasemide as an indicator substance behaves like a challenging-to-process API, only with higher sensitivity and more pronounced effects, e.g., degradation and residual crystallinity. Application of a model formulation containing torasemide will enhance the understanding of the dynamic environment inside an extruder and elucidate the cumulative thermal and hydrolysis effects of the extrusion process. The use of such a formulation will also facilitate rational process development and scaling by establishing clear links between process conditions and CQAs.

  17. Using Flory-Huggins phase diagrams as a pre-formulation tool for the production of amorphous solid dispersions: a comparison between hot-melt extrusion and spray drying.

    Science.gov (United States)

    Tian, Yiwei; Caron, Vincent; Jones, David S; Healy, Anne-Marie; Andrews, Gavin P

    2014-02-01

    Amorphous drug forms provide a useful method of enhancing the dissolution performance of poorly water-soluble drugs; however, they are inherently unstable. In this article, we have used Flory-Huggins theory to predict drug solubility and miscibility in polymer candidates, and used this information to compare spray drying and melt extrusion as processes to manufacture solid dispersions. Solid dispersions were prepared using two different techniques (hot-melt extrusion and spray drying), and characterised using a combination of thermal (thermogravimetric analysis and differential scanning calorimetry), spectroscopic (Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction methods. Spray drying permitted generation of amorphous solid dispersions across a wider drug concentration than melt extrusion. Melt extrusion provided sufficient energy for more intimate mixing to be achieved between drug and polymer, which may improve physical stability. It was also confirmed that stronger drug-polymer interactions might be generated through melt extrusion. Remixing and dissolution of recrystallised felodipine into the polymeric matrices did occur during the modulated differential scanning calorimetry analysis, but the complementary information provided from FTIR confirms that all freshly prepared spray-dried samples were amorphous with the existence of amorphous drug domains within high drug-loaded samples. Using temperature-composition phase diagrams to probe the relevance of temperature and drug composition in specific polymer candidates facilitates polymer screening for the purpose of formulating solid dispersions. © 2013 Royal Pharmaceutical Society.

  18. Micro-scale prediction method for API-solubility in polymeric matrices and process model for forming amorphous solid dispersion by hot-melt extrusion.

    Science.gov (United States)

    Bochmann, Esther S; Neumann, Dirk; Gryczke, Andreas; Wagner, Karl G

    2016-10-01

    A new predictive micro-scale solubility and process model for amorphous solid dispersions (ASDs) by hot-melt extrusion (HME) is presented. It is based on DSC measurements consisting of an annealing step and a subsequent analysis of the glass transition temperature (Tg). The application of a complex mathematical model (BCKV-equation) to describe the dependency of Tg on the active pharmaceutical ingredient (API)/polymer ratio, enables the prediction of API solubility at ambient conditions (25°C). Furthermore, estimation of the minimal processing temperature for forming ASDs during HME trials could be defined and was additionally confirmed by X-ray powder diffraction data. The suitability of the DSC method was confirmed with melt rheological trials (small amplitude oscillatory system). As an example, ball milled physical mixtures of dipyridamole, indomethacin, itraconazole and nifedipine in poly(vinylpyrrolidone-co-vinylacetate) (copovidone) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) were used. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Integrated hot-melt extrusion - injection molding continuous tablet manufacturing platform: Effects of critical process parameters and formulation attributes on product robustness and dimensional stability.

    Science.gov (United States)

    Desai, Parind M; Hogan, Rachael C; Brancazio, David; Puri, Vibha; Jensen, Keith D; Chun, Jung-Hoon; Myerson, Allan S; Trout, Bernhardt L

    2017-10-05

    This study provides a framework for robust tablet development using an integrated hot-melt extrusion-injection molding (IM) continuous manufacturing platform. Griseofulvin, maltodextrin, xylitol and lactose were employed as drug, carrier, plasticizer and reinforcing agent respectively. A pre-blended drug-excipient mixture was fed from a loss-in-weight feeder to a twin-screw extruder. The extrudate was subsequently injected directly into the integrated IM unit and molded into tablets. Tablets were stored in different storage conditions up to 20 weeks to monitor physical stability and were evaluated by polarized light microscopy, DSC, SEM, XRD and dissolution analysis. Optimized injection pressure provided robust tablet formulations. Tablets manufactured at low and high injection pressures exhibited the flaws of sink marks and flashing respectively. Higher solidification temperature during IM process reduced the thermal induced residual stress and prevented chipping and cracking issues. Polarized light microscopy revealed a homogeneous dispersion of crystalline griseofulvin in an amorphous matrix. DSC underpinned the effect of high tablet residual moisture on maltodextrin-xylitol phase separation that resulted in dimensional instability. Tablets with low residual moisture demonstrated long term dimensional stability. This study serves as a model for IM tablet formulations for mechanistic understanding of critical process parameters and formulation attributes required for optimal product performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Investigation of the combined effect of MgO and PEG on the release profile of mefenamic acid prepared via hot-melt extrusion techniques.

    Science.gov (United States)

    Alshehri, Sultan M; Tiwari, Roshan V; Alsulays, Bader B; Ashour, Eman A; Alshetaili, Abdullah S; Almutairy, Bjad; Park, Jun-Bom; Morott, Joseph; Sandhu, Bhupinder; Majumdar, Soumyajit; Repka, Michael A

    2017-09-01

    This study aimed to investigate the combined effect of magnesium oxide (MgO) as an alkalizer and polyethylene glycol (PEG) as a plasticizer and wetting agent in the presence of Kollidon® 12 PF and 17 PF polymer carriers on the release profile of mefenamic acid (MA), which was prepared via hot-melt extrusion technique. Various drug loads of MA and various ratios of the polymers, PEG 3350 and MgO were blended using a V-shell blender and extruded using a twin-screw extruder (16-mm Prism EuroLab, ThermoFisher Scientific, Carlsbad, CA) at different screw speeds and temperatures to prepare a solid dispersion system. Differential scanning calorimetry and X-ray diffraction data of the extruded material confirmed that the drug existed in the amorphous form, as evidenced by the absence of corresponding peaks. MgO and PEG altered the micro-environmental pH to be more alkaline (pH 9) and increased the hydrophilicity and dispersibility of the extrudates to enhance MA solubility and release, respectively. The in vitro release study demonstrated an immediate release for 2 h with more than 80% drug release within 45 min in matrices containing MgO and PEG in combination with polyvinylpyrrolidone when compared to the binary mixture, physical mixture and pure drug.

  1. Downstream processing of a ternary amorphous solid dispersion: The impacts of spray drying and hot melt extrusion on powder flow, compression and dissolution.

    Science.gov (United States)

    Davis, Mark T; Potter, Catherine B; Walker, Gavin M

    2018-06-10

    Downstream processing aspects of a stable form of amorphous itraconazole exhibiting enhanced dissolution properties were studied. Preparation of this ternary amorphous solid dispersion by either spray drying or hot melt extrusion led to significantly different powder processing properties. Particle size and morphology was analysed using scanning electron microscopy. Flow, compression, blending and dissolution were studied using rheometry, compaction simulation and a dissolution kit. The spray dried material exhibited poorer flow and reduced sensitivity to aeration relative to the milled extrudate. Good agreement was observed between differing forms of flow measurement, such as Flow Function, Relative flow function, Flow rate index, Aeration rate, the Hausner ratio and the Carr index. The stability index indicated that both powders were stable with respect to agglomeration, de-agglomeration and attrition. Tablet ability and compressibility studies showed that spray dried material could be compressed into stronger compacts than extruded material. Blending of the powders with low moisture, freely-flowing excipients was shown to influence both flow and compression. Porosity studies revealed that blending could influence the mechanism of densification in extrudate and blended extrudate formulations. Following blending, the powders were compressed into four 500 mg tablets, each containing a 100 mg dose of amorphous itraconazole. Dissolution studies revealed that the spray dried material released drug faster and more completely and that blending excipients could further influence the dissolution rate. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Soluplus®/TPGS-based solid dispersions prepared by hot-melt extrusion equipped with twin-screw systems for enhancing oral bioavailability of valsartan.

    Science.gov (United States)

    Lee, Jae-Young; Kang, Wie-Soo; Piao, Jingpei; Yoon, In-Soo; Kim, Dae-Duk; Cho, Hyun-Jong

    2015-01-01

    Soluplus(®) (SP) and D-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS)-based solid dispersion (SD) formulations were developed by hot-melt extrusion (HME) to improve oral bioavailability of valsartan (VST). HME process with twin-screw configuration for generating a high shear stress was used to prepare VST SD formulations. The thermodynamic state of the drug and its dispersion in the polymers were evaluated by solid-state studies, including Fourier-transform infrared, X-ray diffraction, and differential scanning calorimetry. Drug release from the SD formulations was assessed at pH values of 1.2, 4.0, and 6.8. Pharmacokinetic study was performed in rats to estimate the oral absorption of VST. HME with a high shear rate produced by the twin-screw system was successfully applied to prepare VST-loaded SD formulations. Drug amorphization and its molecular dispersion in the polymer matrix were verified by several solid-state studies. Drug release from SD formulations was improved, compared to the pure drug, particularly at pH 6.8. Oral absorption of drug in rats was also enhanced in SP and TPGS-based SD groups compared to that in the pure drug group. SP and TPGS-based SDs, prepared by the HME process, could be used to improve aqueous solubility, dissolution, and oral absorption of poorly water-soluble drugs.

  3. Design and Evaluation of Topical Diclofenac Sodium Gel Using Hot Melt Extrusion Technology as a Continuous Manufacturing Process with Kolliphor® P407.

    Science.gov (United States)

    Pawar, Jaywant; Narkhede, Rajkiran; Amin, Purnima; Tawde, Vaishali

    2017-08-01

    The aim of the present context was to develop and evaluate a Kolliphor® P407-based transdermal gel formulation of diclofenac sodium by hot melt extrusion (HME) technology; central composite design was used to optimize the formulation process. In this study, we have explored first time ever HME as an industrially feasible and continuous manufacturing technology for the manufacturing of gel formulation using Kolliphor® P407 and Kollisolv® PEG400 as a gel base. Diclofenac sodium was used as a model drug. The HME parameters such as feeding rate, screw speed, and barrel temperature were crucial for the semisolid product development, and were optimized after preliminary trials. For the processing of the gel formulation by HME, a modified screw design was used to obtain a uniform product. The obtained product was evaluated for physicochemical characterization such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), pH measurement, rheology, surface tension, and texture profile analysis. Moreover, it was analyzed for general appearance, spreadibility, surface morphology, and drug content. The optimized gel formulation showed homogeneity and transparent film when applied on a glass slide under microscope, pH was 7.02 and uniform drug content of 100.04 ± 2.74 (SD = 3). The DSC and XRD analysis of the HME gel formulation showed complete melting of crystalline API into an amorphous form. The Kolliphor® P407 and Kollisolv® PEG400 formed excellent gel formulation using HME with consistent viscoelastic properties of the product. An improved drug release was found for the HME gel, which showed a 100% drug release than that of a marketed product which showed only 88% of drug release at the end of 12 h. The Flux value of the HME gel was 106 than that of a marketed formulation, which showed only about 60 value, inferring a significant difference (P process for manufacturing of topical semisolid products.

  4. The impact of hot melt extrusion and spray drying on mechanical properties and tableting indices of materials used in pharmaceutical development.

    Science.gov (United States)

    Iyer, Raman; Hegde, Shridhar; Zhang, Yu-E; Dinunzio, James; Singhal, Dharmendra; Malick, A; Amidon, Gregory

    2013-10-01

    The impact of melt extrusion (HME) and spray drying (SD) on mechanical properties of hypromellose acetate succinate (HPMCAS), copovidone, and their formulated blends was studied and compared with that of reference excipients. Tensile strength (TS), compression pressure (CP), elastic modulus (E), and dynamic hardness (Hd ) were determined along with Hiestand indices using compacts prepared at a solid fraction of ∼0.85. HPMCAS and copovidone exhibited lower Hd , lower CP, and lower E than the reference excipients and moderate TS. HPMCAS was found to be highly brittle based on brittle fracture index values. The CP was 24% and 61% higher for HPMCAS after SD and HME, respectively, than for unprocessed material along with a higher Hd . Furthermore, the TS of HPMCAS and copovidone decreased upon HME. Upon blending melt-extruded HPMCAS with plastic materials such as microcrystalline cellulose, the TS increased. These results suggest that SD and HME could impact reworkability by reducing deformation of materials and in case of HME, likely by increasing density due to heating and shear stress in a screw extruder. A somewhat similar effect was observed for the dynamic binding index (BId ) of the excipients and formulated blends. Such data can be used to quantitate the impact of processing on mechanical properties of materials during tablet formulation development. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

  5. Improving the API dissolution rate during pharmaceutical hot-melt extrusion I: Effect of the API particle size, and the co-rotating, twin-screw extruder screw configuration on the API dissolution rate.

    Science.gov (United States)

    Li, Meng; Gogos, Costas G; Ioannidis, Nicolas

    2015-01-15

    The dissolution rate of the active pharmaceutical ingredients in pharmaceutical hot-melt extrusion is the most critical elementary step during the extrusion of amorphous solid solutions - total dissolution has to be achieved within the short residence time in the extruder. Dissolution and dissolution rates are affected by process, material and equipment variables. In this work, we examine the effect of one of the material variables and one of the equipment variables, namely, the API particle size and extruder screw configuration on the API dissolution rate, in a co-rotating, twin-screw extruder. By rapidly removing the extruder screws from the barrel after achieving a steady state, we collected samples along the length of the extruder screws that were characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) to determine the amount of undissolved API. Analyses of samples indicate that reduction of particle size of the API and appropriate selection of screw design can markedly improve the dissolution rate of the API during extrusion. In addition, angle of repose measurements and light microscopy images show that the reduction of particle size of the API can improve the flowability of the physical mixture feed and the adhesiveness between its components, respectively, through dry coating of the polymer particles by the API particles. Copyright © 2014. Published by Elsevier B.V.

  6. Global approach for the validation of an in-line Raman spectroscopic method to determine the API content in real-time during a hot-melt extrusion process.

    Science.gov (United States)

    Netchacovitch, L; Thiry, J; De Bleye, C; Dumont, E; Cailletaud, J; Sacré, P-Y; Evrard, B; Hubert, Ph; Ziemons, E

    2017-08-15

    Since the Food and Drug Administration (FDA) published a guidance based on the Process Analytical Technology (PAT) approach, real-time analyses during manufacturing processes are in real expansion. In this study, in-line Raman spectroscopic analyses were performed during a Hot-Melt Extrusion (HME) process to determine the Active Pharmaceutical Ingredient (API) content in real-time. The method was validated based on a univariate and a multivariate approach and the analytical performances of the obtained models were compared. Moreover, on one hand, in-line data were correlated with the real API concentration present in the sample quantified by a previously validated off-line confocal Raman microspectroscopic method. On the other hand, in-line data were also treated in function of the concentration based on the weighing of the components in the prepared mixture. The importance of developing quantitative methods based on the use of a reference method was thus highlighted. The method was validated according to the total error approach fixing the acceptance limits at ±15% and the α risk at ±5%. This method reaches the requirements of the European Pharmacopeia norms for the uniformity of content of single-dose preparations. The validation proves that future results will be in the acceptance limits with a previously defined probability. Finally, the in-line validated method was compared with the off-line one to demonstrate its ability to be used in routine analyses. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Elucidation and visualization of solid-state transformation and mixing in a pharmaceutical mini hot melt extrusion process using in-line Raman spectroscopy.

    Science.gov (United States)

    Van Renterghem, Jeroen; Kumar, Ashish; Vervaet, Chris; Remon, Jean Paul; Nopens, Ingmar; Vander Heyden, Yvan; De Beer, Thomas

    2017-01-30

    Mixing of raw materials (drug+polymer) in the investigated mini pharma melt extruder is achieved by using co-rotating conical twin screws and an internal recirculation channel. In-line Raman spectroscopy was implemented in the barrels, allowing monitoring of the melt during processing. The aim of this study was twofold: to investigate (I) the influence of key process parameters (screw speed - barrel temperature) upon the product solid-state transformation during processing of a sustained release formulation in recirculation mode; (II) the influence of process parameters (screw speed - barrel temperature - recirculation time) upon mixing of a crystalline drug (tracer) in an amorphous polymer carrier by means of residence time distribution (RTD) measurements. The results indicated a faster mixing endpoint with increasing screw speed. Processing a high drug load formulation above the drug melting temperature resulted in the production of amorphous drug whereas processing below the drug melting point produced solid dispersions with partially amorphous/crystalline drug. Furthermore, increasing the screw speed resulted in lower drug crystallinity of the solid dispersion. RTD measurements elucidated the improved mixing capacity when using the recirculation channel. In-line Raman spectroscopy has shown to be an adequate PAT-tool for product solid-state monitoring and elucidation of the mixing behavior during processing in a mini extruder. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Hydrostatic extrusion of Cu-Ag melt spun ribbon

    Science.gov (United States)

    Hill, Mary Ann; Bingert, John F.; Bingert, Sherri A.; Thoma, Dan J.

    1998-01-01

    The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process.

  9. Microstructural modelling and lubrication study during zirconium alloy hot extrusion

    International Nuclear Information System (INIS)

    Gaudout, B.

    2009-01-01

    Using torsion tests (with strain rate jumps) and an experimental hot mini-extrusion apparatus, several samples zirconium alloy have been deformed: Zircaloy-4 (high α range) and Zr-1Nb (α + β domain). The fragmentation of the microstructure and post-dynamic grain growth have been examined. The main difference between these two alloys is that Zr-1Nb does not show grain growth during a heat treatment within the α + β domain after hot deformation. The recrystallization volume fraction has been measured on extruded samples with or without heat treatment. These rheological and microstructural data have been used to determine the parameters of a microstructural model including: a work-hardening model (Laaasraoui/Jonas), a continuous dynamic recrystallization model (Gourdet/Montheillet) and a grain growth model. This model leads to a good prediction of recrystallization volume fraction for Zircaloy-4 extrusion. However, the Zr-1Nb model cannot be validated because of the difficulty to observe deformed microstructures. Extrusion process is lubricated with a solid film. Trapping tests show that this lubricant is thermoviscoplastic. Friction along the container and several observations show the lubrication is not realized by a continuous film. Indeed, the heterogeneousness of deformation of these alloys causes a rupture of the lubricant film. Experiments and numerical simulations show that the radial gradient of axial displacement is affected by friction but also by stress softening of the alloys. (author)

  10. Radiation polymerized hot melt pressure sensitive adhesives

    International Nuclear Information System (INIS)

    Pastor, S.D.; Skoultchi, M.M.

    1977-01-01

    Hot melt pressure sensitive adhesive compositions formed by copolymerizing at least one 3-(chlorinated aryloxy)-2-hydroxypropyl ester of an alpha, beta unsaturated carboxylic acid with acrylate based copolymerizable monomers, are described. The resultant ethylenically saturated prepolymer is heated to a temperature sufficient to render it fluid and flowable. This composition is coated onto a substrate and exposed to ultraviolet radiation

  11. Melting, casting, and alpha-phase extrusion of the uranium-2.4 weight percent niobium alloy

    International Nuclear Information System (INIS)

    Anderson, R.C.; Beck, D.E.; Kollie, T.G.; Zorinsky, E.J.; Jones, J.M.

    1981-10-01

    The experimental details of the melting, casting, homogenization, and alpha-phase extrusion process used to fabricate the uranium-2.4 wt % niobium alloy into 46-mm-diameter rods is described. Extrusion defects that were detected by an ultrasonic technique were eliminated by proper choice of extrusion parameters; namely, reduction ratio, ram speed, die angle, and billet preheat temperature

  12. Diclofenac sodium sustained release hot melt extruded lipid matrices.

    Science.gov (United States)

    Vithani, K; Cuppok, Y; Mostafa, S; Slipper, I J; Snowden, M J; Douroumis, D

    2014-08-01

    Sustained release diclofenac sodium (Df-Na) solid lipid matrices with Compritol® 888 ATO were developed in this study. The drug/lipid powders were processed via cold and hot melt extrusion at various drug loadings. The influence of the processing temperatures, drug loading and the addition of excipients on the obtained dissolution rates was investigated. The physicochemical characterization of the extruded batches showed the existence of crystalline drug in the extrudates with a small amount being solubilized in the lipid matrix. The drug content and uniformity on the tablet surface were also investigated by using energy dispersive X-ray microanalysis. The dissolution rates were found to depend on the actual Df-Na loading and the nature of the added excipients, while the effect of the processing temperatures was negligible. The dissolution mechanism of all extruded formulations followed Peppas-Korsemeyer law, based on the estimated determination coefficients and the dissolution constant rates, indicating drug diffusion from the lipid matrices.

  13. Optimized manufacture of nuclear fuel cladding tubes by FEA of hot extrusion and cold pilgering processes

    Science.gov (United States)

    Gaillac, Alexis; Ly, Céline

    2018-05-01

    Within the forming route of Zirconium alloy cladding tubes, hot extrusion is used to deform the forged billets into tube hollows, which are then cold rolled to produce the final tubes with the suitable properties for in-reactor use. The hot extrusion goals are to give the appropriate geometry for cold pilgering, without creating surface defects and microstructural heterogeneities which are detrimental for subsequent rolling. In order to ensure a good quality of the tube hollows, hot extrusion parameters have to be carefully chosen. For this purpose, finite element models are used in addition to experimental tests. These models can take into account the thermo-mechanical coupling conditions obtained in the tube and the tools during extrusion, and provide a good prediction of the extrusion load and the thermo-mechanical history of the extruded product. This last result can be used to calculate the fragmentation of the microstructure in the die and the meta-dynamic recrystallization after extrusion. To further optimize the manufacturing route, a numerical model of the cold pilgering process is also applied, taking into account the complex geometry of the tools and the pseudo-steady state rolling sequence of this incremental forming process. The strain and stress history of the tube during rolling can then be used to assess the damage risk thanks to the use of ductile damage models. Once validated vs. experimental data, both numerical models were used to optimize the manufacturing route and the quality of zirconium cladding tubes. This goal was achieved by selecting hot extrusion parameters giving better recrystallized microstructure that improves the subsequent formability. Cold pilgering parameters were also optimized in order to reduce the potential ductile damage in the cold rolled tubes.

  14. Generation and use of process maps for hot extrusion of seamless tubes for nuclear applications

    International Nuclear Information System (INIS)

    Vaibhaw, Kumar; Jha, S.K.; Saibaba, N.; Jayaraj, R.N.

    2009-01-01

    Full text: Hot extrusion is known as significant bulk deformation step in manufacturing of seamless tube production. Elevated temperature deformation carried out above the recrystallization temperature would enable imposition of large strains in single step. This deformation causes a significant change in the microstructure of the material and depends on extrusion process parameters such as temperature and strain rate (Ram speed). Basic microstructure developed at this deformation stage has significant bearing on the final properties of the material fabricated with subsequent cold working steps. Zirconium alloys and special nuclear grade austenitic stainless steels are two important groups of materials used as structural and core components in thermal and fast reactors world wide respectively. The properties of former alloy are very sensitive to the thermo mechanical fabrication steps initiated with hot extrusion due to their anisotropic deformation behaviour. However, nuclear grade austenitic stainless steels have many variants from their commercial grades in terms of micro and macro alloy chemistry. Factors such as these significantly affect the workability of the materials and require proper selection of extrusion parameters especially working temperature and extrusion speed plays a key role in the quality of the product. Modern developments in processing technology envisage the application of processing maps based on dynamic material model for selection of hot extrusion parameters. The present paper is aimed at bringing out significance of the map in selection of working domain with respect to the industrial process conditions for both groups of nuclear materials mentioned earlier. Developed process maps of certain alloys suggest use of extremely slow strain rate and low temperature extrusion which can not be achieved during bulk processing due to design of equipment and heat transfer constraints in industrial scale production. Attempts are made to highlight

  15. Complex deformation routes for direct recycling aluminium alloy scrap via industrial hot extrusion

    Science.gov (United States)

    Paraskevas, Dimos; Kellens, Karel; Kampen, Carlos; Mohammadi, Amirahmad; Duflou, Joost R.

    2018-05-01

    This paper presents the final results of an industrial project, aiming for direct hot extrusion of wrought aluminium alloy scrap at an industrial scale. Two types of complex deformation/extrusion routes were tested for the production of the same profile, starting from AA6060 scrap in form of machining chips. More specifically scrap-based billets were extruded through: a 2-porthole and a 4-porthole die-set, modified for enhanced scrap consolidation and grain refinement. For comparison reasons, cast billets of the same alloy were extruded through the modified 2-porthole die set. The tensile testing results as well as microstructural investigations show that the 4-porthole extrusion route further improves scrap consolidation compared to the 2-porthole die output. The successful implementation of solid state recycling, directly at industrial level, indicates the technological readiness level of this research.

  16. Study on Hot Deformation Behavior of 7085 Aluminum Alloy during Backward Extrusion Process

    Directory of Open Access Journals (Sweden)

    R. B. Mei

    2015-01-01

    Full Text Available Compression test was carried out and the true stress-strain curves were obtained from the hot compression of 7085 alloy. A numerical simulation on the deformation behavior of 7085 aluminum alloy during the backward extrusion was also performed by finite element method. The results show that dynamic recrystallization occurs in the hot compression of 7085 alloy and the peak stress reaches higher values as the strain rate increases and deformation temperature decreases. The backward extrusion processes include contact deformation, initial deformation, and steady deformation. Severe plastic deformation of shear and compression occurs when the metal flowed into the channel between fillet of punch and wall of die so that the grain size can be refined by backward extrusion. The deformation in the region of top of wall is too small to meet the mechanical properties of requirements and the metal usually needs to be trimmed. The experiments with the same parameters as simulation had been carried out and the experimental cup after extrusion has better quality.

  17. Mechanical properties of copper-lithium alloys produced by mechanic alloyed and hot extrusion

    International Nuclear Information System (INIS)

    Castillo B, Ricardo; Gorziglia S, Ezio; Penaloza V, Augusto

    2004-01-01

    In this work are presented the progress carried out on the characterization of some physical and mechanical properties, together with the determination of the micro mechanism of fracture of the Cu-2% wt Li, that was obtained by mechanical alloying followed hot extrusion at 500 o C and 700 o C. Hardness and tensile mechanical tests were performed together with metallographic and fractographic analysis. The experimental results obtained with powders of the Cu-Li alloy studied are compared with powder of pure copper, under similar test conditions. The results show that by hot extrusion was allowed to obtain very high densification levels for the materials under study. Moreover, it was found that lithium reduce both the tensile strength and elongation, of copper by a mechanism of embrittlement. The results are compares with the literature (au)

  18. Aluminum-graphite composite produced by mechanical milling and hot extrusion

    International Nuclear Information System (INIS)

    Flores-Zamora, M.I.; Estrada-Guel, I.; Gonzalez-Hernandez, J.; Miki-Yoshida, M.; Martinez-Sanchez, R.

    2007-01-01

    Aluminum-graphite composites were produced by mechanical milling followed by hot extrusion. Graphite content was varied between 0 and 1 wt.%. Al-graphite mixtures were initially mixed in a shaker mill without ball, followed by mechanical milling in a High-energy simoloyer mill for 2 h under argon atmosphere. Milled powders were subsequently pressed at ∼950 MPa for 2 min, and next sintered under vacuum for 3 h at 823 K. Finally, sintered products were held for 0.5 h at 823 K and hot extruded using indirect extrusion. Tension and compression tests were carried out to determine the yield stress and maximum stress of the materials. We found that the mechanical resistance increased as the graphite content increased. Microstructural characterization was done by transmission electron microscopy. Al-O-C nanofibers and graphite nanoparticles were observed in extruded samples by transmission electron microscopy. These nanoparticles and nanofibers seemed to be responsible of the reinforcement phenomenon

  19. Effect of composition in the development of carbamazepine hot-melt extruded solid dispersions by application of mixture experimental design.

    Science.gov (United States)

    Djuris, Jelena; Ioannis, Nikolakakis; Ibric, Svetlana; Djuric, Zorica; Kachrimanis, Kyriakos

    2014-02-01

    This study investigates the application of hot-melt extrusion for the formulation of carbamazepine (CBZ) solid dispersions, using polyethyleneglycol-polyvinyl caprolactam-polyvinyl acetate grafted copolymer (Soluplus, BASF, Germany) and polyoxyethylene-polyoxypropylene block copolymer (Poloxamer 407). In agreement with the current Quality by Design principle, formulations of solid dispersions were prepared according to a D-optimal mixture experimental design, and the influence of formulation composition on the properties of the dispersions (CBZ heat of fusion and release rate) was estimated. Prepared solid dispersions were characterized using differential scanning calorimetry, attenuated total reflectance infrared spectroscopy and hot stage microscopy, as well as by determination of the dissolution rate of CBZ from the hot-melt extrudates. Solid dispersions of CBZ can be successfully prepared using the novel copolymer Soluplus. Inclusion of Poloxamer 407 as a plasticizer facilitated the processing and decreased the hardness of hot-melt extrudates. Regardless of their composition, all hot-melt extrudates displayed an improvement in the release rate compared to the pure CBZ, with formulations having the ratio of CBZ : Poloxamer 407 = 1 : 1 showing the highest increase in CBZ release rate. Interactions between the mixture components (CBZ and polymers), or quadratic effects of the components, play a significant role in overall influence on the CBZ release rate. © 2013 Royal Pharmaceutical Society.

  20. Controlling the extrudate swell in melt extrusion additive manufacturing of 3D scaffolds: a designed experiment.

    Science.gov (United States)

    Yousefi, Azizeh-Mitra; Smucker, Byran; Naber, Alex; Wyrick, Cara; Shaw, Charles; Bennett, Katelyn; Szekely, Sarah; Focke, Carlie; Wood, Katherine A

    2018-02-01

    Tissue engineering using three-dimensional porous scaffolds has shown promise for the restoration of normal function in injured and diseased tissues and organs. Rigorous control over scaffold architecture in melt extrusion additive manufacturing is highly restricted mainly due to pronounced variations in the deposited strand diameter upon any variations in process conditions and polymer viscoelasticity. We have designed an I-optimal, split-plot experiment to study the extrudate swell in melt extrusion additive manufacturing and to control the scaffold architecture. The designed experiment was used to generate data to relate three responses (swell, density, and modulus) to a set of controllable factors (plotting needle diameter, temperature, pressure, and the dispensing speed). The fitted regression relationships were used to optimize the three responses simultaneously. The swell response was constrained to be close to 1 while maximizing the modulus and minimizing the density. Constraining the extrudate swell to 1 generates design-driven scaffolds, with strand diameters equal to the plotting needle diameter, and allows a greater control over scaffold pore size. Hence, the modulus of the scaffolds can be fully controlled by adjusting the in-plane distance between the deposited strands. To the extent of the model's validity, we can eliminate the effect of extrudate swell in designing these scaffolds, while targeting a range of porosity and modulus appropriate for bone tissue engineering. The result of this optimization was a predicted modulus of 14 MPa and a predicted density of 0.29 g/cm 3 (porosity ≈ 75%) using polycaprolactone as scaffold material. These predicted responses corresponded to factor levels of 0.6 μm for the plotting needle diameter, plotting pressure of 2.5 bar, melt temperature of 113.5 °C, and dispensing speed of 2 mm/s. The validation scaffold enabled us to quantify the percentage difference for the predictions, which was 9.5% for the

  1. Preparation and evaluation of enteric coated tablets of hot-melt extruded lansoprazole.

    Science.gov (United States)

    Alsulays, Bader B; Kulkarni, Vijay; Alshehri, Sultan M; Almutairy, Bjad K; Ashour, Eman A; Morott, Joseph T; Alshetaili, Abdullah S; Park, Jun-Bom; Tiwari, Roshan V; Repka, Michael A

    2017-05-01

    The objective of this work was to use hot-melt extrusion (HME) technology to improve the physiochemical properties of lansoprazole (LNS) to prepare stable enteric coated LNS tablets. For the extrusion process, we chose Kollidon ® 12 PF (K12) polymeric matrix. Lutrol ® F 68 was selected as the plasticizer and magnesium oxide (MgO) as the alkalizer. With or without the alkalizer, LNS at 10% drug load was extruded with K12 and F68. LNS changed to the amorphous phase and showed better release compared to that of the pure crystalline drug. Inclusion of MgO improved LNS extrudability and release and resulted in over 80% drug release in the buffer stage. Hot-melt extruded LNS was physically and chemically stable after 12 months of storage. Both formulations were studied for compatibility with Eudragit ® L100-55. The optimized formulation was compressed into a tablet followed by coating process utilizing a pan coater using L100-55 as an enteric coating polymer. In a two-step dissolution study, the release profile of the enteric coated LNS tablets in the acidic stage was less than 10% of the LNS, while that in the buffer stage was more than 80%. Drug content analysis revealed the LNS content to be 97%, indicating the chemical stability of the enteric coated tablet after storage for six months. HME, which has not been previously used for LNS, is a valuable technique to reduce processing time in the manufacture of enteric coated formulations of an acid-sensitive active pharmaceutical ingredient as compared to the existing methods.

  2. Influence of twin-screw hot extrusion on linolenic acid retention in flaxseed meal

    International Nuclear Information System (INIS)

    Imran, M.

    2014-01-01

    flaxseed (linum usitatissimum l.) provides multiple nutritional benefits including high quality protein, dietary fiber and is the most abundant source of alpha-linolenic acid (c18:3). This study focuses on the effect of twin-screw hot extrusion on alpha-linolenic acid retention in full-fat flaxseed meal. the ranges of processing variables selected using box-behnken design were barrel exit temperature (bet) of 120-140 degree c; screw speed (ss) of 200-400 rpm; feed rate (fr) of 1-2 kg/h and feed moisture (fm) of 20-30%. The amount of alpha-linolenic acid retention in extruded samples ranged from 89.2% to 99.3%. Optimal operating conditions were stablished; bet (121degree c), ss (388 rpm), fr (1 kg/h) and fm (22.2%) for maximum (99.9%) retention of degree-linolenic acid. This effect was mainly dependent on bet and fm (p degree 0.01), whereas ss and fr imparted a lesser effect (p=0.05). The results of this study demonstrated that the twin-screw hot extrusion can be successfully explored to produce fatty meals with significant fatty acids retention for commercially food or feed purposes. (author)

  3. Study on the Hot Extrusion Process of Advanced Radiation Resistant Oxide Dispersion Strengthened Steel Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Byoungkwon; Noh, Sanghoon; Kim, Kibaik; Kang, Suk Hoon; Chun, Youngbum; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Ferritic/martensitic steel has a better thermal conductivity and swelling resistance than austenitic stainless steel. Unfortunately, the available temperature range of ferritic/martensitic steel is limited at up to 650 .deg. C. Oxide dispersion strengthened (ODS) steels have been developed as the most prospective core structural materials for next generation nuclear systems because of their excellent high strength and irradiation resistance. The material performances of this new alloy are attributed to the existence of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperature in a ferritic/martensitic matrix. This microstructure can be very attractive in achieving superior mechanical properties at high temperatures, and thus, these favorable microstructures should be obtained through the controls of the fabrication process parameters during the mechanical alloying and hot consolidation procedures. In this study, a hot extrusion process for advanced radiation resistant ODS steel tube was investigated. ODS martensitic steel was designed to have high homogeneity, productivity, and reproducibility. Mechanical alloying and hot consolidation processes were employed to fabricate the ODS steels. A microstructure observation and creep rupture test were examined to investigate the effects of the optimized fabrication conditions. Advanced radiation resistant ODS steel has been designed to have homogeneity, productivity, and reproducibility. For these characteristics, modified mechanical alloying and hot consolidation processes were developed. Microstructure observation revealed that the ODS steel has uniformly distributed fine-grain nano-oxide particles. The fabrication process for the tubing is also being propelled in earnest.

  4. Study on the Hot Extrusion Process of Advanced Radiation Resistant Oxide Dispersion Strengthened Steel Tubes

    International Nuclear Information System (INIS)

    Choi, Byoungkwon; Noh, Sanghoon; Kim, Kibaik; Kang, Suk Hoon; Chun, Youngbum; Kim, Tae Kyu

    2014-01-01

    Ferritic/martensitic steel has a better thermal conductivity and swelling resistance than austenitic stainless steel. Unfortunately, the available temperature range of ferritic/martensitic steel is limited at up to 650 .deg. C. Oxide dispersion strengthened (ODS) steels have been developed as the most prospective core structural materials for next generation nuclear systems because of their excellent high strength and irradiation resistance. The material performances of this new alloy are attributed to the existence of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperature in a ferritic/martensitic matrix. This microstructure can be very attractive in achieving superior mechanical properties at high temperatures, and thus, these favorable microstructures should be obtained through the controls of the fabrication process parameters during the mechanical alloying and hot consolidation procedures. In this study, a hot extrusion process for advanced radiation resistant ODS steel tube was investigated. ODS martensitic steel was designed to have high homogeneity, productivity, and reproducibility. Mechanical alloying and hot consolidation processes were employed to fabricate the ODS steels. A microstructure observation and creep rupture test were examined to investigate the effects of the optimized fabrication conditions. Advanced radiation resistant ODS steel has been designed to have homogeneity, productivity, and reproducibility. For these characteristics, modified mechanical alloying and hot consolidation processes were developed. Microstructure observation revealed that the ODS steel has uniformly distributed fine-grain nano-oxide particles. The fabrication process for the tubing is also being propelled in earnest

  5. Klucel™ EF and ELF polymers for immediate-release oral dosage forms prepared by melt extrusion technology.

    Science.gov (United States)

    Mohammed, Noorullah Naqvi; Majumdar, Soumyajit; Singh, Abhilasha; Deng, Weibin; Murthy, Narasimha S; Pinto, Elanor; Tewari, Divya; Durig, Thomas; Repka, Michael A

    2012-12-01

    The objective of this research work was to evaluate Klucel™ hydroxypropylcellulose (HPC) EF and ELF polymers, for solubility enhancement as well as to address some of the disadvantages associated with solid dispersions. Ketoprofen (KPR), a Biopharmaceutics Classification System class II drug with poor solubility, was utilized as a model compound. Preliminary thermal studies were performed to confirm formation of a solid solution/dispersion of KPR in HPC matrix and also to establish processing conditions for hot-melt extrusion. Extrudates pelletized and filled into capsules exhibited a carrier-dependent release with ELF polymer exhibiting a faster release. Tablets compressed from milled extrudates exhibited rapid release owing to the increased surface area of the milled extrudate. Addition of mannitol (MNT) further enhanced the release by forming micro-pores and increasing the porosity of the extrudates. An optimized tablet formulation constituting KPR, MNT, and ELF in a 1:1:1 ratio exhibited 90% release in 15 min similar to a commercial capsule formulation. HPC polymers are non-ionic hydrophilic polymers that undergo polymer-chain-length-dependent solubilization and can be used to enhance solubility or dissolution rate of poorly soluble drugs. Dissolution/release rate could be tailored for rapid-release applications by selecting a suitable HPC polymer and altering the final dosage form. The release obtained from pellets was carrier-dependent and not drug-dependent, and hence, such a system can be effectively utilized to address solubility or precipitation issues with poorly soluble drugs in the gastrointestinal environment.

  6. COMPUTER MODELING OF STRAINS ON PHASE BOUNDARIES IN DUCTILE CAST IRON AT HOT EXTRUSION

    Directory of Open Access Journals (Sweden)

    A. I. Pokrovsky

    2017-01-01

    Full Text Available The computer modeling of the strain distribution in the structure of ductile iron with ferrite-pearlite matrix and inclusions of spherical graphite dependence on increasing degree of deformation during direct hot extrusion was researched. Using a software system of finite-element analysis ANSYS the numerical values of the strains at the phase boundaries: ferrite-perlite, graphiteferrite and also inside the graphite inclusions were defined. The analysis of the strain distribution in the investigated structures was performed and local zones of increased strains were discovered. The results of modeling are compared with metallographic analysis and fracture patterns. The obtained results could be used in the prediction of fracture zones in the cast iron products. 

  7. Tribological characterization of Al7075–graphite composites fabricated by mechanical alloying and hot extrusion

    International Nuclear Information System (INIS)

    Deaquino-Lara, R.; Soltani, N.; Bahrami, A.; Gutiérrez-Castañeda, E.; García-Sánchez, E.; Hernandez-Rodríguez, M.A.L.

    2015-01-01

    Highlights: • Al7075–graphite composites were synthesized by mechanical alloying and hot extrusion. • Effects of graphite content and milling time on the mechanical and wear properties of fabricated composites were analyzed. • Microstructure and worn surfaces of samples were studied by transmission and scanning electron microscope. • The friction coefficient, wear rate and debris thickness of fabricated composite were investigated. - Abstract: Aluminum matrix composites (AMCs) are candidate materials for aerospace and automotive industry owing to their large elastic modulus, improved strength and low wear rate. A simple method for fabrication of Al7075–graphite composites produced by mechanical alloying (MI) and hot extrusion is described in this paper. Effects of milling time (0–10 h) and graphite concentration (0–1.5 wt.%) on friction, hardness and wear resistance of the AMC were investigated. Wear resistance was determined by the pin-on-disk wear method using 20 and 40 N normal loads at a 0.367 m/s sliding velocity. The worn surfaces were examined by scanning electron microscopy (SEM) to identify distinct topographical features for elucidation of the prevailing wear mechanisms. Experimental results indicated considerable improvement in AMC hardness and wear resistance by adding 1.5% G (wt.) and 10 h of milling, showing homogenous distribution of the reinforcement particles in the Al-base metal-matrix composite. It was found that abrasion is the dominant wear mechanism in all extruded composites, whilst a combination of adhesion and delamination seems to be the governing mechanism for the 7075 aluminum alloy

  8. Application of heat treatment and hot extrusion processes to improve mechanical properties of the AZ91 alloy

    Directory of Open Access Journals (Sweden)

    T. Reguła

    2010-04-01

    Full Text Available The main aim of this paper is to evaluate the effects of hot working (extrusion and hest treatment on room temperature mechanical properties of magnesium-based AZ91 alloy. The results were compared with as-cast condition. The examined material had been obtained by gravity casting to permanent moulds and subsequently subjected to heat treatment and/or processed by extrusion at 648 K. Microstructural and mechanical properties of properly prepared specimens were studied. Rm, Rp02 and A5 were determined from tensile tests. Brinell hardness tests were also conducted. The research has shown that hot working of AZ91 alloy provides high mechanical properties unattainable by cast material subjected to heat-treatment. The investigated alloy subjected to hot working and subsequently heat-treated has doubled its strength and considerably improved the elongation - compared with the as-cast material.

  9. Reduced activation ODS ferritic steel - recent development in high speed hot extrusion processing

    Energy Technology Data Exchange (ETDEWEB)

    Oksiuta, Zbigniew [Faculty of Mechanical Engineering, Bialystok Technical University (Poland); Lewandowska, Malgorzata; Kurzydlowski, Krzysztof [Faculty of Materials Science and Engineering, Warsaw University of Technology (Poland); Baluc, Nadine [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, Villigen PSI (Switzerland)

    2010-05-15

    The paper presents the microstructure and mechanical properties of an oxide dispersion strengthened (ODS), reduced activation, ferritic steel, namely the Fe-14Cr-2W-0.3Ti-0.3Y{sub 2}O{sub 3} alloy, which was fabricated by hot isostatic pressing followed by high speed hydrostatic extrusion (HSHE) and heat treatment HT at 1050 C. Transmission electron microscopy (TEM) observations revealed significant differences in the grain size and dislocation density between the as-HIPped and as-HSHE materials. It was also found that the microstructure of the steel is stable after HT. The HSHE process improves significantly the tensile and Charpy impact properties of the as-HIPped steel. The ultimate tensile strength at room temperature increases from 950 up to 1350 MPa, while the upper shelf energy increases from 3.0 up to 6.0 J. However, the ductile-to-brittle transition temperature (DBTT) remains relatively high (about 75 C).These results indicate that HSHE is a promising method for achieving grain refinement and thus improving the mechanical properties of ODS ferritic steels. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  10. Melt extrusion vs. spray drying: The effect of processing methods on crystalline content of naproxen-povidone formulations.

    Science.gov (United States)

    Haser, Abbe; Cao, Tu; Lubach, Joe; Listro, Tony; Acquarulo, Larry; Zhang, Feng

    2017-05-01

    Our hypothesis is that melt extrusion is a more suitable processing method than spray drying to prepare amorphous solid dispersions of drugs with a high crystallization tendency. Naproxen-povidone K25 was used as the model system in this study. Naproxen-povidone K25 solid dispersions at 30% and 60% drug loadings were characterized by modulated DSC, powder X-ray diffraction, FT-IR, and solid-state 13 C NMR to identify phase separation and drug recrystallization during processing and storage. At 30% drug loading, hydrogen bond (H-bond) sites of povidone K25 were not saturated and the glass transition (T g ) temperature of the formulation was higher. As a result, both melt-extruded and spray-dried materials were amorphous initially and remained so after storage at 40°C. At 60% drug loading, H-bond sites were saturated, and T g was low. We were not able to prepare amorphous materials. The initial crystallinity of the formulations was 0.4%±0.2% and 5.6%±0.6%, and increased to 2.7%±0.3% and 21.6%±1.0% for melt-extruded and spray-dried materials, respectively. Spray-dried material was more susceptible to re-crystallization during processing, due to the high diffusivity of naproxen molecules in the formulation matrix and lack of kinetic stabilization from polymer solution. A larger number of crystalline nucleation sites and high surface area made the spray-dried material more susceptible to recrystallization during storage. This study demonstrated the unique advantages of melt extrusion over spray drying for the preparation of amorphous solid dispersions of naproxen at high drug level. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. The corrosion of steels by hot sodium melts

    International Nuclear Information System (INIS)

    Currie, R.

    1996-01-01

    Considerable research has been performed by AEA Technology on the corrosion of steels by hot sodium melts containing sodium hydroxide and sodium oxide. This research has principally been in support of understanding the effects of sodium-water reactions on the internals of fast reactor steam generators. The results however have relevance to sodium fires. It has been determined that the rate of corrosion of steels by melts of pure NaOH can be significantly increased by the addition of Na 2 O. In the case of a sodium-water reaction jet created by a leak of steam into sodium, the composition of the jet varies from 100% sodium through to 100% steam, with a full range of concentrations of NaOH and Na 2 O, depending on axial and radial position. The temperature in the jet also varies with position, ranging from bulk sodium temperature on one boundary to expanded steam temperature on the other boundary, with internal temperatures ranging up to 1300 deg. C, depending on the local pre-reaction mole ratio of steam to sodium. In the case of sodium-water reaction jets, it has been possible to develop a model which predicts the composition of the reaction jet and then, using the data generated on the corrosivity of sodium melts, predict the rate of corrosion of a steel target in the path of the jet. In the case of a spray sodium fire, the sodium will initially contain a concentration of NaOH and the combustion process will generate Na 2 O. If there is sufficient humidity, conversion of some of the Na 2 O to NaOH will also occur. There is therefore the potential for aggressive mixtures of NaOH and Na 2 O to exist on the surface of the sodium droplets. It is therefore possible that the rate of corrosion of steels in the path of the spray may be higher than expected on the basis of assuming that only Na and Na 2 O were present. In the case of a pool sodium fire, potentially corrosive mixtures of NaOH and Na 2 O may be formed at some locations on the surface. This could lead to

  12. Active packaging for topical cosmetic/drug products: a hot-melt extruded preservative delivery device.

    Science.gov (United States)

    Zema, L; Sangalli, M E; Maroni, A; Foppoli, A; Bettero, A; Gazzaniga, A

    2010-06-01

    A delivery device intended for the prolonged release of antimicrobial agents, able to enhance the stability profile of liquid/semi-solid cosmetic/pharmaceutical products for topical application, was proposed in the present study. With the aid of a simulation program based on compartment models, the relevant kinetic and formulation parameters were defined using dehydroacetic acid sodium salt (DHA.Na, Prevan) as the model preservative. Indeed, the overall DHA.Na degradation rate is increased in the presence of formaldehyde releasers that are often employed as co-preservatives. Inert matrices (3 g weight and 18 mm diameter) based on high-density polyethylene (HDPE), possibly consistent with the design of an active packaging meant for preservative delivery, were prepared by hot-melt extrusion. Units with satisfactory physical-technological properties could be obtained up to 50%w/w loads of antimicrobial agent. In an attempt to modify the relevant Fickian release profiles by varying the area exposed to the medium, matrix systems coated with an impermeable film except for one base (CMs) or for the inner surface of a central drilled hole (PCMs) were investigated. On the basis of the n exponent of power equation and the outcome of linear fitting, PCMs were proven able to yield the zero-order release behaviour needed to ensure constant DHA.Na levels over a predetermined time period, as indicated by the simulation process. Copyright 2010 Elsevier B.V. All rights reserved.

  13. 21 CFR 175.230 - Hot-melt strippable food coatings.

    Science.gov (United States)

    2010-04-01

    ..., white For use only as a component of hot-melt strippable food coatings applied to frozen meats and... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Hot-melt strippable food coatings. 175.230 Section 175.230 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  14. In situ production of tantalum carbide nanodispersoids in a copper matrix by reactive milling and hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Manotas-Albor, Milton, E-mail: manotasm@uninorte.edu.co [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Km. 5 vía a Puerto Colombia, Barranquilla (Colombia); Departamento de Ingeniería Mecánica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beauchef 850, Santiago (Chile); Vargas-Uscategui, Alejandro [Laboratorio de Materiales a Nanoescala, Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile); Palma, Rodrigo [Departamento de Ingeniería Mecánica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beauchef 850, Santiago (Chile); Mosquera, Edgar [Laboratorio de Materiales a Nanoescala, Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile)

    2014-06-15

    Highlights: • Tantalum carbide nanodispersoids were obtained in a copper matrix. • Nanodispersoids were obtained by means of reactive milling followed by hot extrusion. • Hexane was used as the liquid medium for the reactive mechanical alloying process. • Hexane provides the carbon (C) needed for the process. • The reaction of tantalum carbide formation takes place in the hot extrusion. - Abstract: This paper presents a study of the in situ production of tantalum carbide nanodispersoids in a copper matrix. The copper matrix composites were produced by means of reactive milling in hexane (C{sub 6}H{sub 14}) followed by hot extrusion. The composite materials were characterized by means of optical emission spectroscopy (OES), X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Vickers micro-hardness. The effect of milling time was analyzed in 10, 20 and 30 h in a composite with a nominal composition Cu–5 vol.% TaC. A systematic increase of the dislocations density and the carbon concentration were observed when the milling time was increased, whereas the crystallite size of the composite matrix decreased. The material milled for 30 h and hot-extruded showed a density of 9037 kg m{sup −3} (98.2% densification) and a softening resistance of 204 HV; however the latter value showed an abrupt drop after an annealing treatment at 923 K for 1 h. Finally, the TEM analysis showed the presence of tantalum carbide (Ta{sub 4}C{sub 3}) nanodispersoids.

  15. The microstructures and mechanical properties of Al-15Si-2.5Cu-0.5Mg/(wt%)B{sub 4}C composites produced through hot pressing technique and subjected to hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, Alpay, E-mail: alpiozer@gmail.com

    2016-11-01

    In this study, B{sub 4}C (5, 10, and 15 wt%) particle-reinforced Ecka Alumix 231{sup ®} aluminum matrix composites were produced through the hot pressing technique. Some of these samples were subjected to hot extrusion as a secondary treatment at 4:1 ratio at a temperature of 555 °C. The obtained samples were subjected to density measurement, hardness test, microstructure analysis, and three-point bending test, and their fracture surfaces were examined. A density of over 99% was found in the samples. Al-rich solid solution and primary Si, CuAl{sub 2}, Al{sub 2}CuMg, and Mg{sub 2}Si phases in the microstructure were determined through X-ray diffraction analysis. Grain sizes were found to be 20 μm and 2 μm in the microstructures of the samples produced through hot pressing technique and of those subjected to additional hot extrusion, respectively. High hardness values were obtained in the samples subjected to hot extrusion. In these samples, wt% B{sub 4}C particle ratio and transverse rupture strength increased considerably. Furthermore, the highest compressive strain value was obtained in the 10 wt% B{sub 4}C particle-reinforced composites subjected to hot extrusion. - Highlights: • Liquid phase formed at the temperature of hot pressing and hot extrusion. • In the samples, over 99.19% density was obtained. • Average matrix grain size was measured to be 2 μm through hot extrusion. • As wt% B{sub 4}C ratio increased, transverse rupture strength values increased. • High compressive strain values were obtained in the hot extrusion samples.

  16. Manufacturing and mechanical property test of the large-scale oxide dispersion strengthened martensitic mother tube by hot isostatic pressing and hot extrusion process

    International Nuclear Information System (INIS)

    Narita, Takeshi; Ukai, Shigeharu; Kaito, Takeji; Ohtsuka, Satoshi; Fujiwara, Masayuki

    2003-09-01

    Mass production capability of Oxide Dispersion Strengthened (ODS) ferritic steel cladding (9Cr) is evaluated in the Phase II of the Feasibility Studies on Commercialized Fast Reactor Cycle System. The cost for manufacturing mother tube is a dominant factor in the total cost for manufacturing ODS ferritic cladding. In this study, the large-scale 9Cr-ODS martensitic mother tube was produced by overseas supplier with mass production equipments for commercialized ODS steels. The process of manufacturing the ODS mother tube consists of raw material powder production, mechanical alloying by high energy ball mill, hot isostatic pressing(HIP), and hot extrusion. Following results were obtained in this study. (1) Micro structure of the ODS steels is equivalent to that of domestic products, and fine oxides are uniformly distributed. The mechanical alloying by large capacity (1 ton) ball mill can be satisfactorily carried out. (2) A large scale mother tube (65 mm OD x 48 mm ID x 10,000 mm L), which can produce about 60 pieces of 3 m length ODS ferritic claddings by four times cold rolling, have been successfully manufactured through HIP and Hot Extrusion process. (3) Rough surface of the mother tubes produced in this study can be improved by selecting the reasonable hot extrusion condition. (4) Hardness and tensile strength of the manufactured ODS steels are lower than domestic products with same chemical composition. This is owing to the high aluminum content in the product, and those properties could be improved by decreasing the aluminum content in the raw material powder. (author)

  17. Application of physical and numerical simulations for interpretation of peripheral coarse grain structure during hot extrusion of AA7020 aluminum alloy

    NARCIS (Netherlands)

    Eivani, A.R.; Zhou, J.

    2017-01-01

    In this research, hot compression test is used to simulate the metallurgical phenomena occurring in the peripheral part of AA7020 aluminum alloy extrudates during hot extrusion and leading to the formation of the peripheral coarse grain (PCG) structure. The temperature profiles at a tracking

  18. Effects of Hot-Hydrostatic Canned Extrusion on the Stock Utilization, Microstructure and Mechanical Properties of TiBw/TC4 Composites with Quasi-Continuous Network.

    Science.gov (United States)

    Feng, Yangju; Li, Bing; Cui, Guorong; Zhang, Wencong

    2017-10-25

    In-situ TiB whisker-reinforced Ti-6Al-4V (TC4) titanium matrix composites (TiBw/TC4) with quasi-continuous networks were successfully fabricated by vacuum hot-pressing sintering. The effects of the hot-hydrostatic canned extrusion on stock utilization, microstructure and mechanical properties of the TiBw/TC4 composites were investigated. It was satisfactory that the utilization of composites could be obviously improved by canned extrusion compared to that extruded without canned extrusion. The microstructure results showed that after canned extrusion the grain was refined and the TiB whiskers were distributed from a random array state to a state in which the whiskers were distributed along the extrusion direction. The properties testing results revealed that the tensile strength, the hardness and the ductility of the composites all significantly improved after extrusion due to the grain refinement and orientation of the TiB whisker caused by extrusion. Tensile fracture results showed that when the TiB whiskers were randomly distributed only part of them played a role in strengthening the matrix during the deformation process (as-sintered composites), while when the TiB whiskers were oriented all whiskers could strengthen the matrix during the tensile testing process (as-extruded composites).

  19. Development of a high speed extrusion concept using a floating screw sleeve for solid-melt-separation

    Science.gov (United States)

    Karrenberg, Gregor; Wortberg, Johannes

    2015-05-01

    The High-Speed-S-Truder with floating screw sleeve is an alternative extrusion concept with solid-melt-separation. A fairly conventional 35 mm screw with a length of 21 D, which is accelerated by a 75 kW gearless, water cooled synchronous drive, conveys the resin into a 60 mm screw sleeve with a length of 10 D. Inside the sleeve the material is plasticizied and discharged into the outer screw channel of the sleeve through radial bores. Only the solid bed remains inside. The development of a melt pool - and thus a decrease of the plasticizing capacity - is avoided. The sleeve is rotated by drag forces only (approximately 10 - 15 % of the screw speed). Due to the low speed of the screw sleeve molten material is conveyed to a 4 D Dynamic Mixing Ring in a gentle manner. The DMRs floating ring and the screw sleeve are directly coupled. The granules in the screw channel are stopped by a barrier on the screw in front of the mixing device. So nearly no unmelted material can pass the system. For temperature management in the plastification and mixing zone a 3-zone heating/air-cooling system is used. Various kinds of experiments with the High-Speed S-Truder were conducted. Reachable throughputs with different types of material (LDPE, LLDPE, PP, PS) have been tested. Also three screw geometries, which are mainly varying in the channel depth, were compared. Experimental results and theoretical background will be described in this paper.

  20. Preparation and Evaluation of Hot-Melt Extruded Patient-Centric Ketoprofen Mini-Tablets.

    Science.gov (United States)

    Alshetaili, Abdullah S; Almutairy, Bjad K; Tiwari, Roshan V; Morott, Joseph T; Alshehri, Sultan M; Feng, Xin; Alsulays, Bader B; Park, Jun-Bom; Zhang, Feng; Repka, Michael A

    2016-01-01

    Bitter tasting drugs represent a large portion of active pharmaceutical ingredients. Mini-tablets are specifically designed for patients with difficulty in swallowing particular in young children up to 10 years of age, geriatric patients and patients with esophagitis. The present study was aimed to prepare, taste-masked mini-tablets, which are easily swallowed dosage forms, primarily to be used by pediatric and geriatric patients. Ketoprofen (10%-50% w/w) and Eudragit® EPO were blended and extruded with a 5-mm strand die and cut into consistent mini-tablets by using an adapted downstream pelletizer. Differential scanning calorimetry and polarized light microscopy-hot stage microscopy studies confirmed that the binary mixtures were miscible under the employed extrusion temperatures. In-vitro release studies showed that drug release was less than 0.5% within the first 2 min in simulated salivary fluid (pH 6.8) and more than 90% in the first 20 min in gastric media (pH 1.0). The results of the electronic tongue analysis were well correlated with the drug release profile of the mini-tablets in the artificial saliva. Scanning electron microscopy revealed no cracks on the surface of the minitablets, confirming that the mini-tablets were compact solids. Chemical imaging confirmed the uniform distribution of ketoprofen inside the polymer matrices. Eudragit® EPO containing ketoprofen at various drug loads were successfully melt extruded into tastedmasked mini-tablets. The reduced drug release at salivary pH correlated well with Astree e-Tongue studies for taste masking efficiency.

  1. Simple additive manufacturing of an osteoconductive ceramic using suspension melt extrusion

    DEFF Research Database (Denmark)

    Slots, Casper; Bonde Jensen, Martin; Ditzel, Nicholas

    2017-01-01

    /calcium phosphate suspension melt for simple additive manufacturing of ceramic tricalcium phosphate implants. METHODS: A wide variety of non-aqueous liquids were tested to determine the formulation of a storable 3D printable tricalcium phosphate suspension ink, and only fatty acid-based inks were found to work...

  2. Analysis and modeling of hot extrusion die for its service life enhancement

    Science.gov (United States)

    Akhtar, Syed Sohail

    Aluminum extrusion finds extensive application in the construction, automobile and aerospace industries. High pressures, elevated temperatures, complex and intricate section geometries lead to repeated mechanical and thermal stresses in the die and affiliated tooling. Product rework and rejects can be traced back to various defects spread over the die life cycle: die design, die manufacture and heat treatment, process parameters, inprocess die maintenance/correction and, billet type and quality. Therefore, improved and efficient service life of die and related tooling used in the extrusion press is one the most important factors in maximizing productivity and minimizing cost for ensuring the economical efficiency of an aluminum extrusion plant. How often a die has to be scrapped and replaced with a new one directly contributes to the commercial viability of producing a certain profile. The focus of the current work is on three distinct yet inter-related studies pertaining to the improvement of aluminum extrusion die. Study-A (Die Failure Analysis) is an investigation of various modes and critical failure types based on industrial data (Chapter-2 ), examination of failed dies and finite element simulation for identification of critical process parameters and design features in die fatigue-life (Chapter-3). In Study-B (Die Surface Hardening Treatment), two-stage controlled gas nitriding process for H13 steel is evaluated, both experimentally and numerically, in terms of nitrided case morphology and properties (Chapter-4) followed by experimental and numerical investigation of the effects of repeated nitriding (Chapter-5), pre-nitriding surface preparation (Chapter-6) and die profile geometry (Chapter-7) on nitriding performance in regard to die service life. In Study-C (Effect of Billet Quality on Die Life), the effect of billet quality and related influencing extrusion parameters on the die service life is investigated based on industrial data and some regression

  3. Development and evaluation of a hot-melt coating technique for enteric coating

    Directory of Open Access Journals (Sweden)

    Arun Trambak Patil

    2012-03-01

    Full Text Available Conventional enteric coating requires the use of organic based polymers which are equally hazardous to the environment and operating personnel. Hot-melt coating avoids the use of solvents and is a safer and time-saving process. The present study was designed to assess the efficacy of hot-melt coating (HMC as an enteric coating technique. Pellets prepared by extrusion spheronization were selected as the core formulation for a model of the gastric irritant drug diclofenac sodium (DFS because of their innate advantages over single-unit formulations. Stearic acid (SA and palmitic acid (PA were evaluated as enteric hot-melt coating materials. HMC was carried out in a specially modified coating pan by applying SA and PA in molten state onto preheated pellets to achieve a coating level of 5-15 %w/w. Hot-melt coated pellets were evaluated for disintegration pH and in vitro dissolution in the pH range 1.2 to 6.8, along with basic micromeritics. SEM of coated pellets showed a uniform and smooth coating. These results indicated that HMC of both SA and PA exhibited very good enteric coating ability. The coated pellets showed negligible drug release in acidic pH. As the pellets were subsequently transferred to a higher pH level, a gradual increase in release of the drug from the pellets was observed with increasing pH of the dissolution media. The release was dependent upon coating extent, providing sustained enteric release as opposed to abrupt release with mixed release kinetics.O revestimento entérico convencional requer o uso de polímeros orgânicos os quais são igualmente danosos ao meio ambiente e ao pessoal que o executa. O revestimento por fusão a quente evita o uso de solventes e é processo mais seguro e que consome menos tempo. O presente estudo foi planejado para avaliar a eficácia do revestimento por fusão a quente (RFQ como técnica de revestimento entérico. Os péletes preparados por esferonização por extrusão foram selecionados como

  4. Application of film-casting technique to investigate drug-polymer miscibility in solid dispersion and hot-melt extrudate.

    Science.gov (United States)

    Parikh, Tapan; Gupta, Simerdeep Singh; Meena, Anuprabha K; Vitez, Imre; Mahajan, Nidhi; Serajuddin, Abu T M

    2015-07-01

    Determination of drug-polymer miscibility is critical for successful development of solid dispersions. This report details a practical method to predict miscibility and physical stability of drug with various polymers in solid dispersion and, especially, in melt extrudates by applying a film-casting technique. Mixtures of itraconazole (ITZ) with hydroxypropylmethylcellulose phthalate (HPMCP), Kollidon(®) VA 64, Eudragit(®) E PO, and Soluplus(®) were film-casted, exposed to 40°C/75% RH for 1 month and then analyzed using differential scanning calorimetry (DSC), powder X-ray diffractometry, and polarized light microscopy (PLM). ITZ had the highest miscibility with HPMCP, being miscible at drug to polymer ratio of 6:4 (w/w). There was a downward trend of lower miscibility with Soluplus(®) (miscible at 3:7, w/w, and a few microcrystals present at 4:6, w/w), Kollidon(®) VA 64 (2:8, w/w) and Eudragit(®) E PO (casting and hot-melt extrusion (HME) using a twin screw extruder. For ITZ-Soluplus(®) mixtures, HME at 4:6 (w/w) resulted in a single phase, whereas drug crystallization was observed at higher drug load. HME of ITZ-Kollidon(®) VA 64 mixtures also correlated well with the miscibility predicted by film casting. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  5. Hot-melt extruded filaments based on pharmaceutical grade polymers for 3D printing by fused deposition modeling.

    Science.gov (United States)

    Melocchi, Alice; Parietti, Federico; Maroni, Alessandra; Foppoli, Anastasia; Gazzaniga, Andrea; Zema, Lucia

    2016-07-25

    Fused deposition modeling (FDM) is a 3D printing technique based on the deposition of successive layers of thermoplastic materials following their softening/melting. Such a technique holds huge potential for the manufacturing of pharmaceutical products and is currently under extensive investigation. Challenges in this field are mainly related to the paucity of adequate filaments composed of pharmaceutical grade materials, which are needed for feeding the FDM equipment. Accordingly, a number of polymers of common use in pharmaceutical formulation were evaluated as starting materials for fabrication via hot melt extrusion of filaments suitable for FDM processes. By using a twin-screw extruder, filaments based on insoluble (ethylcellulose, Eudragit(®) RL), promptly soluble (polyethylene oxide, Kollicoat(®) IR), enteric soluble (Eudragit(®) L, hydroxypropyl methylcellulose acetate succinate) and swellable/erodible (hydrophilic cellulose derivatives, polyvinyl alcohol, Soluplus(®)) polymers were successfully produced, and the possibility of employing them for printing 600μm thick disks was demonstrated. The behavior of disks as barriers when in contact with aqueous fluids was shown consistent with the functional application of the relevant polymeric components. The produced filaments were thus considered potentially suitable for printing capsules and coating layers for immediate or modified release, and, when loaded with active ingredients, any type of dosage forms. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Simple additive manufacturing of an osteoconductive ceramic using suspension melt extrusion.

    Science.gov (United States)

    Slots, Casper; Jensen, Martin Bonde; Ditzel, Nicholas; Hedegaard, Martin A B; Borg, Søren Wiatr; Albrektsen, Ole; Thygesen, Torben; Kassem, Moustapha; Andersen, Morten Østergaard

    2017-02-01

    Craniofacial bone trauma is a leading reason for surgery at most hospitals. Large pieces of destroyed or resected bone are often replaced with non-resorbable and stock implants, and these are associated with a variety of problems. This paper explores the use of a novel fatty acid/calcium phosphate suspension melt for simple additive manufacturing of ceramic tricalcium phosphate implants. A wide variety of non-aqueous liquids were tested to determine the formulation of a storable 3D printable tricalcium phosphate suspension ink, and only fatty acid-based inks were found to work. A heated stearic acid-tricalcium phosphate suspension melt was then 3D printed, carbonized and sintered, yielding implants with controllable macroporosities. Their microstructure, compressive strength and chemical purity were analyzed with electron microscopy, mechanical testing and Raman spectroscopy, respectively. Mesenchymal stem cell culture was used to assess their osteoconductivity as defined by collagen deposition, alkaline phosphatase secretion and de-novo mineralization. After a rapid sintering process, the implants retained their pre-sintering shape with open pores. They possessed clinically relevant mechanical strength and were chemically pure. They supported adhesion of mesenchymal stem cells, and these were able to deposit collagen onto the implants, secrete alkaline phosphatase and further mineralize the ceramic. The tricalcium phosphate/fatty acid ink described here and its 3D printing may be sufficiently simple and effective to enable rapid, on-demand and in-hospital fabrication of individualized ceramic implants that allow clinicians to use them for treatment of bone trauma. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. A method for manufacturing a tool part for an injection molding process, a hot embossing process, a nano-imprint process, or an extrusion process

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to a method for manufacturing a tool part for an injection molding process, a hot embossing process, nano-imprint process or an extrusion process. First, there is provided a master structure (10) with a surface area comprising nanometre-sized protrusions (11...

  8. Mechanical properties and thermal stability of Al–Fe–Ni alloys prepared by centrifugal atomisation and hot extrusion

    International Nuclear Information System (INIS)

    Průša, F.; Vojtěch, D.; Michalcová, A.; Marek, I.

    2014-01-01

    In this work, Al–12Fe and Al–7Fe–5Ni (wt%) alloys prepared by a novel technique including centrifugal atomisation and hot extrusion were studied. The microstructures were investigated using light microscopy, electron scanning microscopy, transmission electron microscopy and X-ray diffraction. The mechanical properties were determined by Vickers hardness measurements and compressive stress–strain tests. To study the thermal stability, the mechanical properties were also measured after 100 h of annealing at 300 °C and 400 °C. In addition, creep tests at a stress of 120 MPa and a temperature of 300 °C were performed. The investigated materials were composed of fine-grained α-Al and intermetallic phases identified as Al 13 Fe 4 and Al 9 FeNi. The Vickers hardness and compressive yield strength were 68 HV5 and 183 MPa, respectively, for the Al–12Fe alloy and 73 HV5 and 226 MPa, respectively, for the Al–7Fe–5Ni alloy. After long-term annealing, the change in the mechanical properties was negligible, indicating the excellent thermal stability of both materials. The creep tests confirmed the highest thermal stability of the Al–7Fe–5Ni alloy with a total compressive creep strain of 15%. The “thermally stable” casting Al–12Si–1Cu–1Mg–1Ni alloy treated by the T6 regime was used as a reference material. The casting alloy exhibited sufficient mechanical properties (hardness and compressive yield strength) at room temperature. However, annealing remarkably softened and reduced its compressive yield strength to almost 50% of the initial values. Additionally, the total creep strain of the casting reference material was almost three times higher than that of the Al–7Fe–5Ni alloy. It has been proven that centrifugally atomised materials quickly compacted via hot extrusion can compete or even exceed the properties of common casting aluminium alloys that are used in automotive industry

  9. Influence of electron beam Irradiation on PP/Piassava fiber composite prepared by melt extrusion process

    International Nuclear Information System (INIS)

    Gomes, Michelle G.; Ferreira, Maiara S.; Oliveira, Rene R.; Silva, Valquiria A.; Teixeira, Jaciele G.; Moura, Esperidiana A.B.

    2013-01-01

    In the latest years, the interest for the use of natural fibers in materials composites polymeric has increased significantly due to their environmental and technological advantages. Piassava fibers (Attalea funifera) have been used as reinforcement in the matrix of thermoplastic and thermoset polymers. In the present work (20%, in mass), piassava fibers with particle sizes equal or smaller than 250 μm were incorporated in the polypropylene matrix (PP) no irradiated and polypropylene matrix containing 10 % and 30 % of polypropylene treated by electron-beam radiation at 40 kGy (PP/PPi/Piassava). The composites PP/Piassava and PP/PPi/Piassava were prepared by using a twin screw extruder, followed by injection molding. The composite material samples obtained were treated by electron-beam radiation at 40 kGy, using a 1.5 MeV electron beam accelerator, at room temperature, in presence of air. After irradiation treatment, the irradiated and non-irradiated specimens tests samples were submitted to thermo-mechanical tests, melt flow index (MFI), sol-gel analysis, X-Ray diffraction (XRD) and scanning electron microscopy (SEM). (author)

  10. Effect of polymer melt wall slip on the flow balance of profile extrusion dies

    Science.gov (United States)

    Carneiro, Olga S.; Ferrás, Luís L.; Pinho, Fernando T.; Nóbrega, João M.

    2013-04-01

    This work describes the implementation of the wall slip boundary condition in an in-house developed 3D numerical code based on the Finite Volume Method. For this purpose, several phenomenological models relating the velocity and the shear stress at the wall were implemented. This new feature is verified using a simple case study, by comparing the numerical results with those obtained through the corresponding analytical solution. Then, the potentialities of the new code are illustrated performing flow simulations of a polymer melt in a complex flow channel. The results obtained show that the slip at the wall influences the flow distribution at the die flow channel outlet. Therefore, and to assess the relevance of slippage in the optimal die geometry, the automatic optimization of a die flow channel, required for the production of a specific thermoplastic profile, is performed using both the no-slip and slip boundary conditions, together with two alternative optimization strategies. It is shown that slip favors the flow balance of the dies and also other issues of its performance.

  11. Dry sliding tribological behavior and mechanical properties of Al2024–5 wt.%B4C nanocomposite produced by mechanical milling and hot extrusion

    International Nuclear Information System (INIS)

    Abdollahi, Alireza; Alizadeh, Ali; Baharvandi, Hamid Reza

    2014-01-01

    Highlights: • Nanostructured Al2024 and Al2024–B 4 C nanocomposite prepared via mechanical milling. • The milled powders formed by hot pressing and then exposed to hot extrusion. • Tribological behavior and mechanical properties of samples were investigated. • Al2024–B 4 C nanocomposite showed a better wear resistance and mechanical properties. - Abstract: In this paper, tribological behavior and mechanical properties of nanostructured Al2024 alloy produced by mechanical milling and hot extrusion were investigated before and after adding B 4 C particles. Mechanical milling was used to synthesize the nanostructured Al2024 in attrition mill under argon atmosphere up to 50 h. A similar process was used to produce Al2024–5 wt.%B 4 C composite powder. The milled powders were formed by hot pressing and then were exposed to hot extrusion in 750 °C with extrusion ratio of 10:1. To study the microstructure of milled powders and hot extruded samples, optical microscopy, transmission electron microscopy and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS) were used. The mechanical properties of samples were also compared together using tension, compression and hardness tests. The wear properties of samples were studied using pin-on-disk apparatus under a 20 N load. The results show that mechanical milling decreases the size of aluminum matrix grains to less than 100 nm. The results of mechanical and wear tests also indicate that mechanical milling and adding B 4 C particles increase strength, hardness and wear resistance of Al2024 and decrease its ductility remarkably

  12. Microstructure and mechanical properties of 2.5 vol. % TiBw/Ti6Al4V composites plates fabricated by hot-hydrostatic canned extrusion

    Science.gov (United States)

    Zhang, Wencong; Zhang, Lingjia; Feng, Yangju; Cui, Guorong; Chen, Wenzhen

    2018-04-01

    Plates of 2.5 vol. % TiB whisker-reinforced Ti6Al4V titanium matrix composites (TiBw/Ti64) with network structure were successfully fabricated by hot-hydrostatic extrusion with steel cup at 1100 °C. The dimensions of plates were about 150mm in length, 27mm in width and 2mm in thickness. After extrusion, the original equiaxed-network structure formed by TiB whiskers still existed, but was compressed in cross-section and stretched in longitudinal section and then the TiB whiskers were directional distribution along the extrusion direction. Furthermore, the mechanical properties results showed that the strength, hardness and ductility of the plates were significantly improved compared to as-sintered composites.

  13. Hot ductility of structural steels melted with the use of direct reduction charge

    International Nuclear Information System (INIS)

    Marchenko, V.N.; Bulat, S.I.; Litvinenko, D.A.

    1982-01-01

    A possibility of the use of direct reduction charge during the open arc melting of the 40Kh2N2MA steel with the subsequent electroslag remelting was investigated. It is shown that the use of such charge free from non-ferrous metal admixtures permits to increase an alloy hot ductility in the hot-brittleness range from 900 up to 1500 deg C. An increase of the deformation rate from 0.1 up to 1 s - 1 increases 1.5-3 times a level of minimum ductility within this temperature range. It is established that antimony and bismuth impurities considerably decrease hot ductility

  14. Impact of polymer type on bioperformance and physical stability of hot melt extruded formulations of a poorly water soluble drug.

    Science.gov (United States)

    Mitra, Amitava; Li, Li; Marsac, Patrick; Marks, Brian; Liu, Zhen; Brown, Chad

    2016-05-30

    Amorphous solid dispersion formulations have been widely used to enhance bioavailability of poorly soluble drugs. In these formulations, polymer is included to physically stabilize the amorphous drug by dispersing it in the polymeric carrier and thus forming a solid solution. The polymer can also maintain supersaturation and promote speciation during dissolution, thus enabling better absorption as compared to crystalline drug substance. In this paper, we report the use of hot melt extrusion (HME) to develop amorphous formulations of a poorly soluble compound (FaSSIF solubility=1μg/mL). The poor solubility of the compound and high dose (300mg) necessitated the use of amorphous formulation to achieve adequate bioperformance. The effect of using three different polymers (HPMCAS-HF, HPMCAS-LF and copovidone), on the dissolution, physical stability, and bioperformance of the formulations was demonstrated. In this particular case, HPMCAS-HF containing HME provided the highest bioavailability and also had better physical stability as compared to extrudates using HPMCAS-LF and copovidone. The data demonstrated that the polymer type can have significant impact on the formulation bioperformance and physical stability. Thus a thorough understanding of the polymer choice is imperative when designing an amorphous solid dispersion formulation, such that the formulation provides robust bioperformance and has adequate shelf life. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Mechanical properties and thermal stability of Al–Fe–Ni alloys prepared by centrifugal atomisation and hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Průša, F., E-mail: Filip.Prusa@vscht.cz; Vojtěch, D.; Michalcová, A.; Marek, I.

    2014-05-01

    In this work, Al–12Fe and Al–7Fe–5Ni (wt%) alloys prepared by a novel technique including centrifugal atomisation and hot extrusion were studied. The microstructures were investigated using light microscopy, electron scanning microscopy, transmission electron microscopy and X-ray diffraction. The mechanical properties were determined by Vickers hardness measurements and compressive stress–strain tests. To study the thermal stability, the mechanical properties were also measured after 100 h of annealing at 300 °C and 400 °C. In addition, creep tests at a stress of 120 MPa and a temperature of 300 °C were performed. The investigated materials were composed of fine-grained α-Al and intermetallic phases identified as Al{sub 13}Fe{sub 4} and Al{sub 9}FeNi. The Vickers hardness and compressive yield strength were 68 HV5 and 183 MPa, respectively, for the Al–12Fe alloy and 73 HV5 and 226 MPa, respectively, for the Al–7Fe–5Ni alloy. After long-term annealing, the change in the mechanical properties was negligible, indicating the excellent thermal stability of both materials. The creep tests confirmed the highest thermal stability of the Al–7Fe–5Ni alloy with a total compressive creep strain of 15%. The “thermally stable” casting Al–12Si–1Cu–1Mg–1Ni alloy treated by the T6 regime was used as a reference material. The casting alloy exhibited sufficient mechanical properties (hardness and compressive yield strength) at room temperature. However, annealing remarkably softened and reduced its compressive yield strength to almost 50% of the initial values. Additionally, the total creep strain of the casting reference material was almost three times higher than that of the Al–7Fe–5Ni alloy. It has been proven that centrifugally atomised materials quickly compacted via hot extrusion can compete or even exceed the properties of common casting aluminium alloys that are used in automotive industry.

  16. Influence of hot rolling and high speed hydrostatic extrusion on the microstructure and mechanical properties of RAF ODS steel

    International Nuclear Information System (INIS)

    Oksiuta, Z.; Kurzydlowski, K.J.; Baluc, N.

    2009-01-01

    Argon gas atomized, pre-alloyed Fe-14Cr-2W-0.3Ti oxide dispersion strengthened (ODS) ferritic steel powder was mechanically alloyed with 0.3Y2O3 (wt.%) nano-particles in attritor ball mill and consolidated by hot isostatic pressing (HIP) at 1150 deg. C under pressure of 200 MPa for 3 hrs. To improve mechanical properties of as HIPped ODS ingots the material was undergone further thermo-mechanical treatment (TMT), namely: hot rolling (HR) at 850 deg. C or high speed hot extrusion (HSHE) at 850 deg. C. After TMT both materials were annealed at 1050 deg. C for 1 h in vacuum. Transmission electron microscopy (TEM) observations of the ODS alloys after TMT and heat treatment exhibited elongated in a longitudinal direction grains with an average size of 75 μm. However, an equiaxed, smaller than 500 nm grains were also found in the microstructure of both materials. Different size and morphology of oxides particles were also observed. Bigger, about 150 nm Ti-Al-O particles were usually located at grain boundaries whereas Y-Ti-O nanoclusters of about 5 nm were uniformly distributed in ODS steel matrix. The Charpy impact tests revealed significantly better about 90% (5.8 J) upper shelf energy (USE) of material after HSHE but ductile to brittle transition temperature (DBTT) of both alloys was unsatisfactory. As-HR ODS steel has shown DBTT of about 55 deg. C whereas HSHE ODS steel has about 75 deg. C. This relatively high values of transition temperature were probably caused by oxides particles present at grain boundaries of the ODS alloys which decreased fracture properties of the ODS steels. High temperature tensile properties of both ODS alloys are found to be satisfactory in full range of the testing temperature from 23 up to 750 deg. C. However, about 15% better UTS and YS0.2 (1350 MPa and 1285 MPa, respectively) as well as ductility were measured in the case of the as-HSHE ODS steel. These results indicates that HSHE process of the ODS steel can be considered as more

  17. The influence of Ni addition and hot-extrusion on the microstructure and tensile properties of Al–15%Mg2Si composite

    International Nuclear Information System (INIS)

    Emamy, M.; Khodadadi, M.; Honarbakhsh Raouf, A.; Nasiri, N.

    2013-01-01

    Highlights: ► Ni content on the microstructure and tensile properties of Al–Mg 2 Si composite. ► Ni changed the size of primary Mg 2 Si from 42 μm to 17 μm. ► Higher UTS and elongation values obtained by addition of 5 wt% Ni. ► Fracture behavior changed from brittle to ductile by Ni addition and extrusion. - Abstract: The effects of nickel addition and hot-extrusion on the microstructure and tensile properties of in situ Al–15%Mg 2 Si composite specimens have been investigated. Al–15%Mg 2 Si composite ingots were prepared by an in situ process and different amounts of nickel (0.1, 0.3, 0.5, 1.0, 3.0 and 5.0 wt% Ni) were added to the remelted composite. Optical microscopy (OM) and scanning electron microscopy (SEM) indicated that Ni addition changes the morphology of both primary and eutectic Mg 2 Si phases and decreases the size of primary Mg 2 Si particles from 42 μm to 17 μm. Hot-extrusion was found to be powerful in breaking the eutectic network and changing the size and morphology of pseudo-eutectic Mg 2 Si phase. The results obtained from tensile testing revealed that both Ni addition and hot-extrusion process improve ultimate tensile strength (UTS) and elongation values. Fracture surface examinations revealed a transition from brittle fracture mode in as-cast composite to ductile fracture in hot-extruded composite after Ni addition. This can be attributed to the changes in size and morphology of primary and eutectic Mg 2 Si phases and also the formation of more and finer α-Al phase

  18. Influence of hot rolling and high speed hydrostatic extrusion on the microstructure and mechanical properties of an ODS RAF steel

    Energy Technology Data Exchange (ETDEWEB)

    Oksiuta, Z., E-mail: oksiuta@pb.edu.pl [Bialystok Technical University, Faculty of Mechanical Engineering, Wiejska 45c, 15-352 Bialystok (Poland); Lewandowska, M.; Kurzydlowski, K.J. [Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02-504 Warsaw (Poland); Baluc, N. [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, 5232 Villigen PSI (Switzerland)

    2011-02-15

    An argon gas atomized, pre-alloyed Fe-14Cr-2W-0.3Ti (wt.%) reduced activation ferritic (RAF) steel powder was mechanically alloyed with 0.3wt.% Y{sub 2}O{sub 3} nano-particles in an attritor ball mill and consolidated by hot isostatic pressing at 1150 {sup o}C under a pressure of 200 MPa for 3 h. In the aim to improve its mechanical properties the ODS steel was then submitted to a thermo-mechanical treatment (TMT): hot rolling (HR) at 850 deg. C or high speed hydrostatic extrusion (HSHE) at 900 deg. C, followed by heat treatment (HT). Transmission electron microscopy (TEM) observations of the ODS alloys after TMT and heat treatment revealed the presence of elongated grains in the longitudinal direction, with an average width of 8 {mu}m and an average length of 75 {mu}m, and equiaxed grains, a few microns in diameter, in the transverse direction. Two populations of oxide particles were observed by TEM: large Ti-Al-O particles, up to 250 nm in diameter, usually located at the grain boundaries and small Y-Ti-O nanoclusters, about 2.5 nm in diameter, uniformly distributed in the matrix. Charpy impact tests revealed that the HSHE material exhibits a larger upper shelf energy (5.8 J) than the HR material (2.9 J). The ductile-to-brittle transition temperature of both alloys is relatively high, in the range of 55-72 deg. C. Tensile mechanical properties of both ODS alloys were found satisfactory over the full range of investigated temperatures (23-750 deg. C). The HSHE material exhibits better tensile strength and ductility than the HR material. These results indicate that HSHE can be considered as a promising TMT method for improving the mechanical properties of ODS RAF steels.

  19. On the Prediction of Hot Tearing in Al-to-Steel Welding by Friction Melt Bonding

    Science.gov (United States)

    Jimenez-Mena, N.; Jacques, P. J.; Drezet, J. M.; Simar, A.

    2018-04-01

    Aluminum alloy AA6061 was welded to dual-phase steel 980 (DP980) by the friction melt bonding (FMB) process. Hot tears have been suppressed by controlling the thermomechanical cycle. In particular, the welding speed and the thermal conductivity of the backing plate have been optimized. A finite-element thermomechanical model coupled with the Rappaz-Drezet-Gremaud (RDG) criterion has been used to explain these experimental observations. The hot tear susceptibility has been reduced with large thermal gradients and with the formation of a cellular microstructure. Both effects are favored by a backing plate made of a material with high thermal conductivity, such as copper.

  20. Water jet intrusion into hot melt concomitant with direct-contact boiling of water

    Energy Technology Data Exchange (ETDEWEB)

    Sibamoto, Yasuteru [Japan Atomic Energy Research Inst., Tokai Research Establishment, Tokai, Ibaraki (Japan)

    2005-08-01

    Boiling of water poured on surface of high-temperature melt (molten metal or metal oxide) provides an efficient means for heat exchange or cooling of melt. The heat transfer surface area can be extended by forcing water into melt. Objectives of the present study are to elucidate key factors of the thermal and hydrodynamic interactions for the water jet injection into melt (Coolant Injection mode). Proposed applications include in in-vessel heat exchangers for liquid metal reactor and emergency measures for cooling of molten core debris in severe accidents of light water reactor. Water penetration into melt may occurs also as a result of fuel-coolant interaction (FCI) in modes other than CI, it is anticipated that the present study contributes to understand the fundamental mechanism of the FCI process. The previous works have been limited on understanding the melt-water interaction phenomena in the water-injection mode because of difficulty in experimental measurement where boiling occurs in opaque invisible hot melt unlike the melt-injection mode. We conducted visualization and measurement of melt-water-vapor multiphase flow phenomena by using a high-frame-rate neutron radiography technique and newly-developed probes. Although limited knowledge, however, has been gained even such an approach, the experimental data were analyzed deeply by comparing with the knowledge obtained from relevant matters. As a result, we succeeded in revealing several key phenomena and validity in the conditions under which stable heat transfer is established. Moreover, a non-intrusive technique for measurement of the velocity and pressure fields adjacent to a moving free surface is developed. The technique is based on the measurement of fluid surface profile, which is useful for elucidation of flow mechanism accompanied by a free surface like the present phenomena. (author)

  1. Forming of High-strength Steels Using a Hot-melt Dry Lubricant

    DEFF Research Database (Denmark)

    Hörnström, Sven-Erik; Karlsson, Erik; Olsson, Mikael

    2008-01-01

    during forming resulting in seizure of the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number of concepts have been developed in order to reduce the tendency to galling in metal forming, including the development of new dry lubricants, new forming tool...... steel grades and improved surface engineering treatments such as the deposition of low friction CVD and PVD coatings. In the present study the performance of a hot-melt dry lubricant in the forming of hot and cold rolled and hot-dip galvanized high strength steel has been evaluated and compared...... with a conventional rust protection oil using four different tests methods, i.e. a strip reduction test, a bending under tension test, a stretch-forming test and a pin-on disc test. In the tests, two different cold work tool steels, a conventional steel grade and a nitrogen alloyed PM steel grade were evaluated...

  2. Different effects of silica added internal or external on in vitro dissolution of indomethacin hot-melt extrudates.

    Science.gov (United States)

    Xia, Yulong; Yuan, Meng; Deng, Yueyang; Ke, Xue; Ci, Tianyuan

    2017-12-20

    The purpose of this work was to investigate the effect on the dissolution behavior when silica was added in different ways. The solid dispersion was prepared by hot-melt extrusion (HME) using indomethacin (IND) as a model drug and Kollidon VA64 as a carrier. In order to change the dissolution behavior, the silica was added during or after the HME respectively, to obtain the corresponding silica internal-added solid dispersion (InSD) and silica external-added solid dispersion (ExSD). According to the results, the internal-added silicon dioxide could reduce the dissolution rate from 66.91%/h to 24.12%/h and the water infiltration rate from 0.37mm/h to 0.16mm/h in the phosphate buffer solution (PBS) of pH 6.8, so the formulation of InSD had a significant sustained release effect. But the infiltration rate of the ExSD was increased to 13.22mm/h when silica was added external, and the density of VA64 in the powder was decreased from 541.87mg/cm3 to 141.87mg/cm3, leading to a weak resistance to the external force, and the powder was easy to be dispersed after wetted by water so that the formulation of ExSD had a relatively higher dissolution rate. This phenomenon was more visible when the phosphate buffer solution was changed to pH 5.6 in which the API was more difficult to be dissolved. Accordingly, different addition ways of aerosil would change release behavior of the HME preparation. Copyright © 2017. Published by Elsevier B.V.

  3. Description of the heating and expansion process of a water drop enclosed in a hot melt

    International Nuclear Information System (INIS)

    Froehlich, G.; Berg, E. von.

    1985-11-01

    In the present study a simple model for the description of the heating- and expansion-process of a water drop enclosed in hot melt is developed. The model is valid between the first contact of melt and water up to the beginning of evaporation. A possible superheating by retardation of ebullition is disregarded. The balance equations for energy, mass and momentum as well as the equation of state are integrated over the radial space coordinate in both media using appropriate profiles of temperature, pressure and velocity. Thereby a system of coupled ordinary differential equations is formed for the variables of the model which are now time dependent only. The equations are solved numerically by means of a FORTRAN-program. The influence of parameters (melt-temperature, heat-transfer-coefficient between melt and water as well as drop radius) are studied. It is shown that always very rapidly a vapor-layer forms around the water drop, while the inner part of the drop did not yet 'notice' anything of the heating process. An approximation formula for the time-transfer-coefficients between melt and water. Due to this approximation, the time up to incipience of evaporation grows proportional to the drop radius, which means that in the frame of the present model even small droplets won't evaporate as a whole instantaneously. (orig.) [de

  4. Enhanced performance of nano-sized SiC reinforced Al metal matrix nanocomposites synthesized through microwave sintering and hot extrusion techniques

    Directory of Open Access Journals (Sweden)

    M. Penchal Reddy

    2017-10-01

    Full Text Available In the present study, nano-sized SiC (0, 0.3, 0.5, 1.0 and 1.5 vol% reinforced aluminum (Al metal matrix composites were fabricated by microwave sintering and hot extrusion techniques. The structural (XRD, SEM, mechanical (nanoindentation, compression, tensile and thermal properties (co-efficient of thermal expansion-CTE of the developed Al-SiC nanocomposites were studied. The SEM/EDS mapping images show a homogeneous distribution of SiC nanoparticles into the Al matrix. A significant increase in the strength (compressive and tensile of the Al-SiC nanocomposites with the addition of SiC content is observed. However, it is noticed that the ductility of Al-SiC nanocomposites decreases with increasing volume fraction of SiC. The thermal analysis indicates that CTE of Al-SiC nanocomposites decreases with the progressive addition of hard SiC nanoparticles. Overall, hot extruded Al 1.5 vol% SiC nanocomposites exhibited the best mechanical and thermal performance as compared to the other developed Al-SiC nanocomposites. Keywords: Al-SiC nanocomposites, Microwave sintering, Hot extrusion, Mechanical properties, Thermal expansion

  5. An Extrusion Spheronization Approach to Enable a High Drug Load Formulation of a Poorly Soluble Drug with a Low Melting Surfactant.

    Science.gov (United States)

    Tatavarti, Aditya; Kesisoglou, Filippos

    2015-11-01

    Vitamin E tocopherol polyethylene glycol succinate (TPGS) is a non-ionic surface active agent, known to enhance the bioavailability of lipophilic compounds via wettability, solubility, and in some cases permeability enhancement. MK-0536 is an anti-retroviral drug with poor wettability and solubility and a high dose. Based on pharmacokinetic studies in dogs and humans, use of vitamin E TPGS in oral solid formulations of MK-0536 provides desired PK characteristics. The use of vitamin E TPGS, however, in solid dosage forms is limited because of the processing challenges resulting from its waxy nature and low melting temperature (∼37°C). The current study, for the first time, demonstrates the use of an alternative low pressure extrusion and spheronization approach to enable high loadings of the poorly soluble, poorly compactable drug and relatively high levels of vitamin E TPGS. This approach not only aided in mitigating processing challenges arising from most high energy process steps such as milling, compression, and coating, but also enabled a higher drug load formulation that provided superior bioperformance relative to a conventional high shear wet granulated formulation. An encapsulated dosage form consisting of pellets prepared by extrusion spheronization with 75% (w/w) MK-0536 and 10% (w/w) vitamin E TPGS was developed. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  6. Improving significantly the failure strain and work hardening response of LPSO-strengthened Mg-Y-Zn-Al alloy via hot extrusion speed control

    Science.gov (United States)

    Tan, Xinghe; Chee, Winston; Chan, Jimmy; Kwok, Richard; Gupta, Manoj

    2017-07-01

    The effect of hot extrusion speed on the microstructure and mechanical properties of MgY1.06Zn0.76Al0.42 (at%) alloy strengthened by the novel long-period stacking ordered (LPSO) phase was systematically investigated. Increase in the speed of extrusion accelerated dynamic recrystallization of α-Mg via particle-stimulated nucleation and grain growth in the alloy. The intensive recrystallization and grain growth events weakened the conventional basal texture and Hall-Petch strengthening in the alloy which led to significant improvement in its failure strain from 4.9% to 19.6%. The critical strengthening contribution from LPSO phase known for attributing high strength to the alloy was observed to be greatly undermined by the parallel competition from texture weakening and the adverse Hall-Petch effect when the alloy was extruded at higher speed. Absence of work hardening interestingly observed in the alloy extruded at lower speed was discussed in terms of its ultra-fine grained microstructure which promoted the condition of steady-state defect density in the alloy; where dislocation annihilation balances out the generation of new dislocations during plastic deformation. One approach to improve work hardening response of the alloy to prevent unstable deformation and abrupt failure in service is to increase the grain diameter in the alloy by judiciously increasing the extrusion speed.

  7. COMPUTER MODELING IN DEFORM-3D FOR ANALYSIS OF PLASTIC FLOW IN HIGH-SPEED HOT EXTRUSION OF BIMETALLIC FORMATIVE PARTS OF DIE TOOLING

    Directory of Open Access Journals (Sweden)

    I. V. Kachanov

    2015-01-01

    Full Text Available The modern development of industrial production is closely connected with the use of science-based and high technologies to ensure competitiveness of the manufactured products on the world market. There is also much tension around an energy- and resource saving problem which can be solved while introducing new technological processes and  creation of new materials that provide productivity increase through automation and improvement of tool life. Development and implementation of such technologies are rather often considered as time-consuming processes  which are connected with complex calculations and experimental investigations. Implementation of a simulation modelling for materials processing using modern software products serves an alternative to experimental and theoretical methods of research.The aim of this paper is to compare experimental results while obtaining bimetallic samples of a forming tool through the method of speed hot extrusion and the results obtained with the help of computer simulation using DEFORM-3D package and a finite element method. Comparative analysis of plastic flow of real and model samples has shown that the obtained models provide high-quality and reliable picture of plastic flow during high-speed hot extrusion. Modeling in DEFORM-3D make it possible to eliminate complex calculations and significantly reduce a number of experimental studies while developing new technological processes.

  8. Dynamics of upper mantle rocks decompression melting above hot spots under continental plates

    Science.gov (United States)

    Perepechko, Yury; Sorokin, Konstantin; Sharapov, Victor

    2014-05-01

    Numeric 2D simulation of the decompression melting above the hot spots (HS) was accomplished under the following conditions: initial temperature within crust mantle section was postulated; thickness of the metasomatized lithospheric mantle is determined by the mantle rheology and position of upper asthenosphere boundary; upper and lower boundaries were postulated to be not permeable and the condition for adhesion and the distribution of temperature (1400-2050°C); lateral boundaries imitated infinity of layer. Sizes and distribution of lateral points, their symmetry, and maximum temperature varied between the thermodynamic condition for existences of perovskite - majorite transition and its excess above transition temperature. Problem was solved numerically a cell-vertex finite volume method for thermo hydrodynamic problems. For increasing convergence of iterative process the method of lower relaxation with different value of relaxation parameter for each equation was used. The method of through calculation was used for the increase in the computing rate for the two-layered upper mantle - lithosphere system. Calculated region was selected as 700 x (2100-4900) km. The time step for the study of the asthenosphere dynamics composed 0.15-0.65 Ma. The following factors controlling the sizes and melting degree of the convective upper mantle, are shown: a) the initial temperature distribution along the section of upper mantleb) sizes and the symmetry of HS, c) temperature excess within the HS above the temperature on the upper and lower mantle border TB=1500-2000oC with 5-15% deviation but not exceed 2350oC. It is found, that appearance of decompression melting with HS presence initiate primitive mantle melting at TB > of 1600oC. Initial upper mantle heating influence on asthenolens dimensions with a constant HS size is controlled mainly by decompression melting degree. Thus, with lateral sizes of HS = 400 km the decompression melting appears at TB > 1600oC and HS

  9. Preparation of acetaminophen capsules containing beads prepared by hot-melt direct blend coating.

    Science.gov (United States)

    Pham, Loan; Christensen, John M

    2014-02-01

    Twelve hydrophobic coating agents were assessed for their effects on drug release after coating sugar cores by a flexible hot-melt coating method using direct blending. Drug-containing pellets were also produced and used as cores. The cores were coated with single or double wax layers containing acetaminophen (APAP). The harder the wax, the slower the resultant drug releases from single-coated beads. Wax coating can be deposited on cores up to 28% of the beads final weight and reaching 58% with wax and drug. Carnauba-coated beads dissolved in approximately 6 h releasing 80% of the loaded drug. Applying another wax layer extended drug release over 20 h, while still delivering 80% of the loaded drug. When drug-containing pellets (33-58% drug loading) were used as cores, double wax-coated pellets exhibited a near zero-order drug release for 16 h, releasing 80% of the loaded drug delivering 18 mg/h. The simple process of hot-melt coating by direct blending of pellet-containing drug-coated formulations provides excellent options for immediate and sustained release formulations when higher lipid coating or drug loading is warranted. Predicted plasma drug concentration time profiles using convolution and in vitro drug release properties of the beads were performed for optimal formulations.

  10. Evaluation of Graphite Fiber/Polyimide PMCs from Hot Melt vs Solution Prepreg

    Science.gov (United States)

    Shin, E. Eugene; Sutter, James K.; Eakin, Howard; Inghram, Linda; McCorkle, Linda; Scheiman, Dan; Papadopoulos, Demetrios; Thesken, John; Fink, Jeffrey E.

    2002-01-01

    Carbon fiber reinforced high temperature polymer matrix composites (PMC) have been extensively investigated as potential weight reduction replacements of various metallic components in next generation high performance propulsion rocket engines. The initial phase involves development of comprehensive composite material-process-structure-design-property-in-service performance correlations and database, especially for a high stiffness facesheet of various sandwich structures. Overview of the program plan, technical approaches and current multi-team efforts will be presented. During composite fabrication, it was found that the two large volume commercial prepregging methods (hot-melt vs. solution) resulted in considerably different composite cure behavior. Details of the process-induced physical and chemical modifications in the prepregs, their effects on composite processing, and systematic cure cycle optimization studies will be discussed. The combined effects of prepregging method and cure cycle modification on composite properties and isothermal aging performance were also evaluated.

  11. Evaluation of Graphite Fiber/Polyimide PMCs from Hot Melt versus Solution Prepreg

    Science.gov (United States)

    Shin, Eugene E.; Sutter, James K.; Eakin, Howard; Inghram, Linda; McCorkle, Linda; Scheiman, Dan; Papadopoulos, Demetrios; Thesken, John; Fink, Jeffrey E.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Carbon fiber reinforced high temperature polymer matrix composites (PMC) have been extensively investigated as potential weight reduction replacements of various metallic components in next generation high performance propulsion rocket engines. The initial phase involves development of comprehensive composite material-process-structure-design-property in-service performance correlations and database, especially for a high stiffness facesheet of various sandwich structures. Overview of the program plan, technical approaches and current multi-team efforts will be presented. During composite fabrication, it was found that the two large volume commercial prepregging methods (hot-melt vs. solution) resulted in considerably different composite cure behavior. Details of the process-induced physical and chemical modifications in the prepregs, their effects on composite processing, and systematic cure cycle optimization studies will be discussed. The combined effects of prepregging method and cure cycle modification on composite properties and isothermal aging performance were also evaluated.

  12. Selective Laser Melting of Hot Gas Turbine Components: Materials, Design and Manufacturing Aspects

    DEFF Research Database (Denmark)

    Goutianos, Stergios

    2017-01-01

    are built additively to nearly net shape. This allows the fabrication of arbitrary complex geometries that cannot be made by conventional manufacturing techniques. However, despite the powerful capabilities of SLM, a number of issues (e.g. part orientation, support structures, internal stresses), have......Selective Laser Melting (SLM) allows the design and manufacturing of novel parts and structures with improved performance e.g. by incorporating complex and more efficient cooling schemes in hot gas turbine parts. In contrast to conventional manufacturing of removing material, with SLM parts...... to be considered in order to manufacture cost-effective and high quality parts at an industrial scale. These issues are discussed in the present work from an engineering point of view with the aim to provide simple quidelines to produce high quality SLM parts....

  13. Applications of web produced by hot air assisted melt differential electrospinning method

    International Nuclear Information System (INIS)

    Bubakir, Mahmoud M; Li, Haoyi; Wu, Weifeng; Li, Xiaohu; Ma, Shuai; Yang, Weimin

    2014-01-01

    Melt electrospinning, a technique that has gained increasing attention since it easily can generate continuous ultrafine fibers directly from polymer melts without the use of any solvent. Therefore, it is considered as a safe, cost effective, and environmental friendly technique. However, with all those great advantages, the technique still suffers some drawbacks such as: large fiber diameter and low throughput. The hot air assisted melt differential electrospinning (MDES) is a new technique invented by our research team that can solve or eliminate those drawbacks. The most important features of our used apparatus are: Needleless nozzle that could generate multiple Taylor cones around the bottom edge of the nozzle, which can result in a high throughput. The stretching force acting on the jets can be further strengthened by an air current provided by an air pressure gun. Interference between the high voltage supply and temperature sensors could be prevented through the grounding of the nozzle. The ultrafine pp webs produced using the same apparatus was in the micro/nano scale with a diameter of 600nm-6um and a smooth surface. Porosity of the webs ranges from 86.5%-99.4% when different collecting devices are used. The resultant ultrafine webs were applied in three areas: oil sorption, water treatment, and hydrophilic PP membrane. The results were very promising as for oil the sorption capacity was 129.0g/g; for water treatment, the rejection rate for 3um particles was 95%. And for the hydrophilic PP membrane, the water sorption capacity was 12.3 g/g

  14. Effect of hot extrusion, other constituents, and temperature on the strength and fracture of polycrystalline MgO

    Energy Technology Data Exchange (ETDEWEB)

    Rice, R.W. (W.R. Grace and Co.-Conn, Columbia, MD (United States))

    1993-12-01

    Improved agreement was confirmed between the Petch intercept and single-crystal yield stresses at 22 C. Hot-extruded MgO crystal specimens stressed parallel with the resultant axial texture (1) gave the highest and least-scattered strength-grain size results at 22 C, (2) showed direct fractographic evidence of microplastic initiated fracture at 22 C and showed macroscopic yield at 1,315 and especially 1,540 C, and (3) fractured entirely via transgranular cleavage, except for intergranular failure initiation from one or a few grain boundary surfaces exposed on the subsequent fracture surface, mainly at 1,540 C. Hot-extruded, hot-pressed MgO billets gave comparable strength when fracture initiated transgranularly, but lower strength when fracture initiated from one or especially a few grain boundary surfaces exposed on the fracture. The extent and frequency of such boundary fracture increased with test temperature. While oxide additions of [<=] 5% or impurities in hot-pressed or hot-extruded MgO can make limited strength increases at larger grain sizes, those having limited solubility can limit strength at finer grain sizes, as can coarser surface finish. Overall, MgO strength is seen as a balance between flaw and microplastic controlled failure, with several parameters shifting the balance.

  15. Creating Drug Solubilization Compartments via Phase Separation in Multicomponent Buccal Patches Prepared by Direct Hot Melt Extrusion-Injection Molding

    NARCIS (Netherlands)

    Alhijjaj, Muqdad; Bouman, Jacob; Wellner, Nikolaus; Belton, Peter; Qi, Sheng

    2015-01-01

    Creating in situ phase separation in solid dispersion based formulations to allow enhanced functionality of the dosage form, such as improving dissolution of poorly soluble model drug as well as being mucoadhesive, can significantly maximize the in vitro and in vivo performance of the dosage

  16. Hot working behavior of selective laser melted and laser metal deposited Inconel 718

    Science.gov (United States)

    Bambach, Markus; Sizova, Irina

    2018-05-01

    The production of Nickel-based high-temperature components is of great importance for the transport and energy sector. Forging of high-temperature alloys often requires expensive dies, multiple forming steps and leads to forged parts with tolerances that require machining to create the final shape and a large amount of scrap. Additive manufacturing offers the possibility to print the desired shapes directly as net-shape components, requiring only little additional effort in machining. Especially for high-temperature alloys carrying a large amount of energy per unit mass, additive manufacturing could be more energy-efficient than forging if the energy contained in the machining scrap exceeds the energy needed for powder production and laser processing. However, the microstructure and performance of 3d-printed parts will not reach the level of forged material unless further expensive processes such as hot-isostatic pressing are used. Using the design freedom and possibilities to locally engineer material, additive manufacturing could be combined with forging operations to novel process chains, offering the possibility to reduce the number of forging steps and to create near-net shape forgings with desired local properties. Some innovative process chains combining additive manufacturing and forging have been patented recently, but almost no scientific knowledge on the workability of 3D printed preforms exists. The present study investigates the flow stress and microstructure evolution during hot working of pre-forms produced by laser powder deposition and selective laser melting (Figure 1) and puts forward a model for the flow stress.

  17. Influence of lidocaine forms (salt vs. freebase) on properties of drug-Eudragit® L100-55 extrudates prepared by reactive melt extrusion.

    Science.gov (United States)

    Liu, Xu; Ma, Xiangyu; Kun, Eucharist; Guo, Xiaodi; Yu, Zhongxue; Zhang, Feng

    2018-06-05

    This study examines the preparation of sustained-release lidocaine polyelectrolyte complex using reactive melt extrusion. Eudragit L100-55 was selected as the ionic polymer. The influence of drug forms (freebase vs. hydrochloride salt) on lidocaine-Eudragit L100-55 interactions, physical stability, and dissolution properties of extrudates was investigated. It was confirmed by DSC, FT-IR and Raman spectroscopy that polyelectrolyte could only form via the acid-base reaction between Eudragit L100-55 and lidocaine freebase. Due to this ionic interaction, the lidocaine extrudate was physically more stable than the lidocaine hydrochloride extrudate during the storage under stressed condition. Drug release from lidocaine extrudate was a function of drug solubility, polymer solubility, drug-polymer interaction, and drug-induced microenvironment pH. At 30% drug loading, extrudate exhibited sustained release in aqueous media at pH 1.2 and 4.5. Due to the alkaline microenvironment pH induced by dissolved lidocaine, Eudragit L100-55 was solubilized and sustained-release was not achieved in water and aqueous media at pH 5.5. In comparison, lidocaine hydrochloride induced an acidic microenvironment. Drug release of lidocaine hydrochloride extrudate was similar at pH 1.2, 4.5, 5.5 and water with drug being released over 10 hours. The release of lidocaine hydrochloride from the extrudates in these media was primarily controlled by microenvironment pH. It is concluded that different forms of lidocaine resulted in different drug-polymer interactions and distinctive physicochemical properties of extrudates. Copyright © 2018. Published by Elsevier B.V.

  18. Determination of surface energies of hot-melt extruded sugar-starch pellets.

    Science.gov (United States)

    Yeung, Chi-Wah; Rein, Hubert

    2018-02-01

    Hot-melt extruded sugar-starch pellets are an alternative for commercial sugar spheres, but their coating properties remain to be studied. Both the European Pharmcopoeia 8.6 and the United States Pharmacopoeia 40 specify the composition of sugar-starch pellets without giving requirements for the manufacturing process. Due to various fabrication techniques, the physicochemical properties of pellets may differ. Therefore, the adhesion energies of three coating dispersions (sustained, enteric and immediate release) on different types of pellets were investigated. In this context, the surface energies of various kinds of corn starch (normal, waxy, high-amylose) and sucrose pellets were analyzed using the sessile drop method, whereas the surface tensions of the coating dispersions were examined using the pendant drop method. The adhesion forces were calculated from the results of these studies. Furthermore, sugar spheres were characterized in terms of particle size distribution, porosity and specific surface area. An increase of the pellets' sucrose content leads to a more porous surface structure, which gives them an enhanced wetting behavior with coating dispersions. The adhesion energies of extruded sugar-starch pellets are similar to those of commercial sugar spheres, which comply with pharmacopeial requirements. Both types of pellets are equally suited for coating.

  19. Processing effects in production of composite prepreg by hot melt impregnation

    Science.gov (United States)

    Chmielewski, C.; Jayaraman, K.; Petty, C. A.

    1993-06-01

    The hot melt impregnation process for producing composite prepreg has been studied. The role of the exit die is highlighted by operating without impregnation bars. Experimental results show that when a fiber tow is pulled through a resin bath and then through a wedge shaped die, the total resin mass fraction and the extent of resin impregnation in the tow increase with the processing viscosity. The penetration of resin into a fiber bundle is greater when the resin viscosity is higher. This trend is unchanged over a range of tow speeds up to the breaking point. A theoretical model is developed to describe the effect of processing conditions and die geometry on the degree of impregnation. Calculations with this model indicate that for a given die geometry, the degree of impregnation increases from 58 percent to 90 percent as the ratio of the clearance between the tow and the die wall, to the total die gap is decreased from 0.15 to 0.05. Physical arguments related to the effective viscosity of the prepreg show that the clearance ratio is independent of the tow speed, but decreases as the ratio of the effective shear viscosity of the prepreg to the resin viscosity increases. This provides a connection between the experimental results obtained with varying resin viscosity and the computational results obtained with varying clearance values at the die inlet.

  20. Fabrication and Characterizations of Hot-Melt Extruded Nanocomposites Based on Zinc Sulfate Monohydrate and Soluplus

    Directory of Open Access Journals (Sweden)

    Song Yi Lee

    2017-09-01

    Full Text Available Zinc sulfate monohydrate (ZnSO4-loaded nanocomposites (NCs were fabricated by using a hot-melt extruder (HME system. Soluplus (SP was adopted as an amphiphilic polymer matrix for HME processing. The micro-size of ZnSO4 dispersion was reduced to nano-size by HME processing with the use of SP. ZnSO4 could be homogeneously dispersed in SP through HME processing. ZnSO4/SP NCs with a 75 nm mean diameter, a 0.1 polydispersity index, and a −1 mV zeta potential value were prepared. The physicochemical properties of ZnSO4/SP NCs and the existence of SP in ZnSO4/SP NCs were further investigated by solid-state studies. Nano-size range of ZnSO4/SP NC dispersion was maintained in the simulated gastrointestinal environments (pH 1.2 and 6.8 media. No severe toxicity in intestinal epithelium after oral administration of ZnSO4/SP NCs (at 100 mg/kg dose of ZnSO4, single dosing was observed in rats. These results imply that developed ZnSO4/SP NC can be used as a promising nano-sized zinc supplement formulation. In addition, developed HME technology can be widely applied to fabricate nanoformulations of inorganic materials.

  1. Carbon materials as new nanovehicles in hot-melt drug deposition

    International Nuclear Information System (INIS)

    Bielicka, Agnieszka; Wiśniewski, Marek; Terzyk, Artur P; Gauden, Piotr A; Furmaniak, Sylwester; Bieniek, A; Roszek, Katarzyna; Kowalczyk, Piotr

    2013-01-01

    The application of commercially available carbon materials (nanotubes and porous carbons) for the preparation of drug delivery systems is studied. We used two types of carbon nanotubes (CNT) and two activated carbons as potential materials in so-called hot-melt drug deposition (HMDD). The materials were first studied using Raman spectroscopy. Paracetamol was chosen as a model drug. The performed thermal analysis, kinetics, and adsorption–desorption studies revealed that nanoaggregates are formed between carbon nanotubes. In contrast, in pores of activated carbon we do not observe this process and the drug adsorption phenomenon mechanism is simply the filling of small pores. The formation of nanoaggregates was confirmed by the results of GCMC (grand canonical Monte Carlo) simulations and the study of the surface area on nitrogen adsorption–desorption isotherms. The application of carbon nanotubes in HMDD offers the possibility of controlling the rate of drug delivery. Performed MTT tests of nanotubes and drug-loaded nanotubes show that the observed decrease in cell viability number is caused by the influence of the cytostatic properties of nanotubes—they inhibit the proliferation of cells. The carbon nanotubes studied in this paper are essentially nontoxic. (paper)

  2. Alcohol dose dumping: The influence of ethanol on hot-melt extruded pellets comprising solid lipids.

    Science.gov (United States)

    Jedinger, N; Schrank, S; Mohr, S; Feichtinger, A; Khinast, J; Roblegg, E

    2015-05-01

    The objective of the present study was to investigate interactions between alcohol and hot-melt extruded pellets and the resulting drug release behavior. The pellets were composed of vegetable calcium stearate as matrix carrier and paracetamol or codeine phosphate as model drugs. Two solid lipids (Compritol® and Precirol®) were incorporated into the matrix to form robust/compact pellets. The drug release characteristics were a strong function of the API solubility, the addition of solid lipids, the dissolution media composition (i.e., alcohol concentration) and correspondingly, the pellet wettability. Pellets comprising paracetamol, which is highly soluble in ethanol, showed alcohol dose dumping regardless of the matrix composition. The wettability increased with increasing ethanol concentrations due to higher paracetamol solubilities yielding increased dissolution rates. For pellets containing codeine phosphate, which has a lower solubility in ethanol than in acidic media, the wettability was a function of the matrix composition. Dose dumping occurred for formulations comprising solid lipids as they showed increased wettabilities with increasing ethanol concentrations. In contrast, pellets comprising calcium stearate as single matrix component showed robustness in alcoholic media due to wettabilities that were not affected by the addition of ethanol. The results clearly indicate that the physico-chemical properties of the drug and the matrix systems are crucial for the design of ethanol-resistant dosage forms. Moreover, hydrophobic calcium stearate can be considered a suitable matrix system that minimizes the risk of ethanol-induced dose dumping for certain API's. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Numerical simulation of fragmentation of hot metal and oxide melts with the computer code IVA3

    International Nuclear Information System (INIS)

    Mussa, S.; Tromm, W.

    1994-01-01

    The phenomena of fragmentation of melts caused by water-inlet from the bottom with the computer code IVA3/11,12,13/ are investigated. With the computer code IVA3 three-component-multiphase flows can be numerically simulated. Two geometrical models are used. Both consist of a cylindrical vessel for water lying beneath a cylindrical vessel for melt. The vessels are connected to each other through a hole. Steel and UO 2 melts are. The following parameters were varied: the type of the melt (steel,UO 2 ), the water supply pressure and the geometry of the hole in the bottom plate through which the water and melt vessels are connected. As results of the numerical simulations temperature and pressure versus time curves are plotted. Additionally the volume flow rates and the volume fractions of the various phases in the vessels and the increase in surface and enthalpy of the melt during the time of simulation are depicted. With steel melts the rate of fragmentation increases with increasing water pressure and melt temperature, whereby stable channels are formed in the melt layer showing a very low flow resistance for steam. With UO 2 the formations of channels are also observed. However, these channels are not so stable that they eventually break apart and lead to the fragmentation of the UO 2 melt in drops. The fragmentation of the steel melt in water vessel is less than that of UO 2 . No essential solidification of the melt is observed in the respective duration of the simulations. However, a small drop in the melt temperature is observed. With a slight or no water pressure the melt flows from the upper vessel into the water vessel via the connecting hole. The processes take place in a very slow manner and with such a low steam production so that despite the occuring pressure peaks no sign of steam explosions could be observed. (orig./HP) [de

  4. Primitive magmas at five Cascade volcanic fields: Melts from hot, heterogeneous sub-arc mantle

    Science.gov (United States)

    Bacon, C.R.; Bruggman, P.E.; Christiansen, R.L.; Clynne, M.A.; Donnelly-Nolan, J. M.; Hildreth, W.

    1997-01-01

    ; and OIB-source-like domains. Lavas with arc and intraplate (OIB) geochemical signatures were erupted close to HAOT, and many lavas are blends of two or more magma types. Pre-eruptive H2O contents of HAOT, coupled with phase-equilibrium studies, suggest that these magmas were relatively dry and last equilibrated in the mantle wedge at temperatures of ???1300??C and depths of ???40 km, virtually at the base of the crust. Arc basalt and basaltic andesite represent greater extents of melting than HAOT, presumably in the same general thermal regime but at somewhat lower mantle separation temperatures, of domains of sub-arc mantle that have been enriched by a hydrous subduction component derived from the young, relatively hot Juan de Fuca plate. The primitive magmas originated by partial melting in response to adiabatic upwelling within the mantle wedge. Tectonic extension in this part of the Cascade arc, one characterized by slow oblique convergence, contributes to mantle upwelling and facilitates eruption of primitive magmas.

  5. Comparison of structure, morphology, and leach characteristics of multi-phase ceramics produced via melt processing and hot isostatic pressing

    Science.gov (United States)

    Dandeneau, Christopher S.; Hong, Tao; Brinkman, Kyle S.; Vance, Eric R.; Amoroso, Jake W.

    2018-04-01

    Melt processing of multi-phase ceramic waste forms offers potential advantages over traditional solid-state synthesis methods given both the prevalence of melters currently in use and the ability to reduce the possibility of airborne radionuclide contamination. In this work, multi-phase ceramics with a targeted hollandite composition of Ba1.0Cs0.3Cr1.0Al0.3Fe1.0Ti5.7O16 were fabricated by melt processing at 1675 °C and hot isostatic pressing (HIP) at 1250 and 1300 °C. X-ray diffraction analysis (XRD) confirmed hollandite as the major phase in all specimens. Zirconolite/pyrochlore peaks and weaker perovskite reflections were observed after melt processing, while HIP samples displayed prominent perovskite peaks and low-intensity zirconolite reflections. Melt processing produced specimens with large (>50 μm) well-defined hollandite grains, while HIP yielded samples with a more fine-grained morphology. Elemental analysis showed "islands" rich in Cs and Ti across the surface of the 1300 °C HIP sample, suggesting partial melting and partitioning of Cs into multiple phases. Photoemission data revealed multiple Cs 3d spin-orbit pairs for the HIP samples, with the lower binding energy doublets likely corresponding to Cs located in more leachable phases. Among all specimens examined, the melt-processed sample exhibited the lowest fractional release rates for Rb and Cs. However, the retention of Sr and Mo was greater in the HIP specimens.

  6. Microstructure origin of hot spots in textured laser zone melting Bi-2212 monoliths

    International Nuclear Information System (INIS)

    Lera, F; Angurel, L A; Rojo, J A; Mora, M; Recuero, S; Arroyo, M P; Andres, N

    2005-01-01

    Hot spots are one of the main limitations in the development of large-scale high-power applications with superconducting materials. The application of digital speckle interferometry to detect inhomogeneous heating on ceramic superconductors allows the determining of a hot spot location in these materials before any damage is caused to the material. The technique detects deformations that are induced in the material due to dilatation, attaining a resolution of 0.45 μm /fringe. In this paper this technique has been applied to analyse the heating generation in Bi-2212 superconducting monoliths at room temperature and in operation conditions. In the first case a homogeneous heating is obtained, leading to a parallel fringe pattern. In the second case, a situation with an inhomogeneous heating origin has been detected. Once the position of this hot spot is determined, microstructure studies have been performed to determine which defects are responsible for hot spot generation

  7. Freezing Range, Melt Quality, and Hot Tearing in Al-Si Alloys

    Science.gov (United States)

    Uludağ, Muhammet; Çetin, Remzi; Dispinar, Derya

    2018-02-01

    In this study, three different aluminum-silicon alloys (A356, A413, and A380) that have different solidification morphology and solidification ranges were examined with an aim to evaluate the hot tearing susceptibility. T-shape mold and Constrained Rod Casting (CRC) mold were used for the characterization. Reduced Pressure Test (RPT) was used to quantify the casting quality by measuring bifilm index. It was found that bifilm index and solidification range have an important role on the hot tearing formation. As it is known, bifilms can cause porosity and in this case, it was shown that porosity formed by bifilms decreased hot tearing tendency. As the freezing range of alloy increases, bifilms find the time to unravel that reduces hot tearing. However, for eutectic alloy (A413), due to zero freezing range, regardless of bifilm content, hot tearing was never observed. A380.1 alloy had the highest tendency for hot tearing due to having the highest freezing range among the alloys investigated in this work.

  8. Application of ICH Q9 Quality Risk Management Tools for Advanced Development of Hot Melt Coated Multiparticulate Systems.

    Science.gov (United States)

    Stocker, Elena; Becker, Karin; Hate, Siddhi; Hohl, Roland; Schiemenz, Wolfgang; Sacher, Stephan; Zimmer, Andreas; Salar-Behzadi, Sharareh

    2017-01-01

    This study aimed to apply quality risk management based on the The International Conference on Harmonisation guideline Q9 for the early development stage of hot melt coated multiparticulate systems for oral administration. N-acetylcysteine crystals were coated with a formulation composing tripalmitin and polysorbate 65. The critical quality attributes (CQAs) were initially prioritized using failure mode and effects analysis. The CQAs of the coated material were defined as particle size, taste-masking efficiency, and immediate release profile. The hot melt coated process was characterized via a flowchart, based on the identified potential critical process parameters (CPPs) and their impact on the CQAs. These CPPs were prioritized using a process failure mode, effects, and criticality analysis and their critical impact on the CQAs was experimentally confirmed using a statistical design of experiments. Spray rate, atomization air pressure, and air flow rate were identified as CPPs. Coating amount and content of polysorbate 65 in the coating formulation were identified as critical material attributes. A hazard and critical control points analysis was applied to define control strategies at the critical process points. A fault tree analysis evaluated causes for potential process failures. We successfully demonstrated that a standardized quality risk management approach optimizes the product development sustainability and supports the regulatory aspects. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  9. Hot-melt sub- and outercoating combined with enteric aqueous coating to improve the stability of aspirin tablets

    Directory of Open Access Journals (Sweden)

    Xiuzhi Wang

    2017-05-01

    Full Text Available Aspirin is apt to hydrolyze. In order to improve its stability, a new method has been developed involving the application of hot-melt sub- and outercoating combined with enteric aqueous coating. The main aim was to investigate the influence of these factors on the stability of ASA and understand how they work. Satisfactory storage stability were obtained when the aspirin tablet core coated with Eudragit L30D55 film was combined with glycerin monostearate (GMS as an outercoat. Hygroscopicity testing indicated that the moisture penetrating into the tablet may result in a significant change in the physical properties of the coating film observed by scanning electron microscopy. Investigation of the compatibility between the drug and film excipients shows that the talc and methacrylic acid had a significant catalytic effect on ASA. A hypothesis was proposed that the hydrolysis of ASA enteric coated tablets (ASA-ECT was mostly concentrated in the internal film and the interfaces between the film and tablet core. In conclusion, hot-melt coating technology is an alternative to subcoating or outercoating. Also, GMS sub-coating was a better choice for forming a stable barrier between the tablet core and the polymer coating layer, and increases the structure and chemical stability.

  10. [Rapid detection of hot spot mutations of FGFR3 gene with PCR-high resolution melting assay].

    Science.gov (United States)

    Li, Shan; Wang, Han; Su, Hua; Gao, Jinsong; Zhao, Xiuli

    2017-08-10

    To identify the causative mutations in five individuals affected with dyschondroplasia and develop an efficient procedure for detecting hot spot mutations of the FGFR3 gene. Genomic DNA was extracted from peripheral blood samples with a standard phenol/chloroform method. PCR-Sanger sequencing was used to analyze the causative mutations in the five probands. PCR-high resolution melting (HRM) was developed to detect the identified mutations. A c.1138G>A mutation in exon 8 was found in 4 probands, while a c.1620C>G mutation was found in exon 11 of proband 5 whom had a mild phenotype. All patients were successfully distinguished from healthy controls with the PCR-HRM method. The results of HRM analysis were highly consistent with that of Sanger sequencing. The Gly380Arg and Asn540Lys are hot spot mutations of the FGFR3 gene among patients with ACH/HCH. PCR-HRM analysis is more efficient for detecting hot spot mutations of the FGFR3 gene.

  11. Continuous production of controlled release dosage forms based on hot-melt extruded gum arabic: Formulation development, in vitro characterization and evaluation of potential application fields.

    Science.gov (United States)

    Kipping, Thomas; Rein, Hubert

    2016-01-30

    Controlled release matrices based on gum arabic are prepared by applying a continuous hot-melt extrusion technology: the pre-mixture consisting of gum arabic and the incorporated API is plasticized by a co-rotating twin-screw extruder, an intermediate strand is formed by a round nozzle. Single dosed matrices are prepared by cutting the semi elastic strand with a rotary fly cutter. Paracetamol and phenazone are used as model drug substances. High drug loadings up to 70% can be realized. Matrices are characterized concerning their crystalline structure, in vitro dissolution, disintegration time and various physical parameters including glass transition temperature (Tg). Release characteristic behavior is mainly influenced by erosion of the matrices. At higher drug loadings also diffusion based transport gain importance. The solubility of the API shows an influence on the erosion rate of the matrix and should therefore be considered during formulation development. Tg is mainly influenced by the solubility of the API in the surrounding matrix. High soluble phenazone shows a decrease, whereas paracetamol addition has nearly no influence on the Tg of the polymeric system. Activation energy (EA) of the glass transition is determined via dynamic mechanical analysis. The addition of APIs leads to a reduction of EA indicating an increased molecular movement at Tg region compared to placebo extrudates. X-ray diffraction is used to determine the crystalline state of the extruded matrices and interaction between matrix and incorporated APIs. The production of thin layer matrices is an interesting option to provide a fast drug delivery to the oral cavity. High mechanical strength combined with fast disintegration times can be a great advantage for the development of oro-dispersible tablets. A great benefit of the evaluated processing technology is the simple adaption of the final dose by varying either the cutting length or the diameter of the nozzle resulting in a cost

  12. The origin of weld seam defects related to metal flow in the hot extrusion of aluminium alloys en AW-6060 and en AW-6082

    NARCIS (Netherlands)

    Bakker, A.J. den; Werkhoven, R.J.; Sillekens, W.H.; Katgerman, L.

    2014-01-01

    Longitudinal weld seams are an intrinsic feature in hollow extrusions produced with porthole dies. As these joins occur along the entire extruded length, it is desirable that these weld seams have a minimal impact on the structural integrity of the extrudate. In particular, defects associated with

  13. How deep, how hot: comparing pressure and temperature estimates from amphibole and rhyolite-MELTS thermobarometry

    Science.gov (United States)

    Pamukcu, A. S.; Gualda, G. A.

    2013-12-01

    Accurately constraining the pressure and temperature of magma residence is problematic, but it is key to understanding the structure and evolution of magmatic systems. Various thermometers exist (Fe-Ti oxides, Ti-in-zircon, Zr-in-sphene, etc.), but there are fewer barometers that can be applied to volcanic rocks. Most barometers capitalize on amphibole, a relatively common mineral whose composition is sensitive to pressure and temperature changes. Glass composition is a function of pressure for magmas saturated in quartz and feldspar, and a new thermobarometer based on rhyolite-MELTS simulations using glass (matrix glass and crystal-hosted glass inclusions) compositions has been recently proposed. We compare results from amphibole and matrix glass thermobarometry. We focus on outflow high-silica rhyolite pumice from the Peach Spring Tuff (CA-NV-AZ, USA), which are characterized by sanidine+plagioclase×quartz+amphibole+sphene in a high-silica rhyolite glass matrix. Compositional variations in amphibole are slight and described by edenite and Ti-Tschermak substitution, with little Al-Tschermak substitution, suggesting small changes in temperature but not in pressure. Plagioclase compositions are also nearly homogeneous. Thus, we expect thermobarometry results to cluster around a single pressure and temperature, making these samples excellent candidates for comparing thermobarometers. Amphibole×plagioclase thermobarometry reveals: - Amphibole-plagioclase: results vary widely depending on the calibration (e.g. 150-420 MPa, 520-730 °C); combined Anderson & Smith (1995) barometer with Holland & Blundy (1990) thermometer is most consistent, suggesting crystallization at 230 MPa, 680 °C. - Amphibole-only: calibrations give significantly different results (75-115 MPa, 770-960 °C [Ridolfi et al. 2010]; 400-950 MPa, 800-950°C [Ridolfi & Renzulli 2012]). Results suggest the recent re-calibration is particularly unreliable for these rocks, and the earlier calibration is

  14. Numerical study of natural melt convection in cylindrical cavity with hot walls and cold bottom sink

    Directory of Open Access Journals (Sweden)

    Ahmanache Abdennacer

    2013-01-01

    Full Text Available Numerical study of natural convection heat transfer and fluid flow in cylindrical cavity with hot walls and cold sink is conducted. Calculations are performed in terms of the cavity aspect ratio, the heat exchanger length and the thermo physical properties expressed via the Prandtl number and the Rayleigh number. Results are presented in the form of isotherms, streamlines, average Nusselt number and average bulk temperature for a range of Rayleigh number up to 106. It is observed that Rayleigh number and heat exchanger length influences fluid flow and heat transfer, whereas the cavity aspect ratio has no significant effects.

  15. Observations of crystallization and melting in poly(ethylene oxide)/poly(methyl methacrylate) blends by hot-stage atomic-force microscopy

    NARCIS (Netherlands)

    Pearce, R.; Vancso, Gyula J.

    1998-01-01

    The binary blend of poly(ethylene oxide)/atactic poly(methyl methacrylate) is examined using hot-stage atomic-force microscopy (AFM) in conjunction with differential scanning calorimetry and optical microscopy. It was found possible to follow in real time the melting process, which reveals itself to

  16. IMPORTANT DEGRADATIONS IN POLYETHYLENE TERAPHTALATE EXTRUSION PROCESS

    Directory of Open Access Journals (Sweden)

    Şule ALTUN

    2003-01-01

    Full Text Available Polyethylene terephthalate (PET is one of the most used thermo-plastic polymers. The total consumption of PET has been about 30 million tons in the year 2000. Polyester fibers constitute about 60 % of total synthetic fibers consumption. During extrusion, PET polymer is faced to thermal, thermo-oxidative and hydrolytic degradation, which result in severe reduction in its molecular weight, thereby adversely affecting its subsequent melt processability. Therefore, it is essential to understand degradation processes of PET during melt extrusion.

  17. Design of sustained release pellets of ferrous fumarate using cow ghee as hot-melt coating agent.

    Science.gov (United States)

    Sakarkar, Dinesh M; Dorle, Avinash K; Mahajan, Nilesh Manoharrao; Sudke, Suresh Gendappa

    2013-07-01

    The objective of the present study was to design ferrous fumarate (FF) sustained release (SR) pellets using of cow ghee (CG) as an important hot-melt coating (HMC) agent. The pellets were coated by HMC technique using CG and ethyl cellulose composition by conventional coating pan without the use of spray system. FF formulated as pellets and characterized with regard to the drug content and physico-chemical properties. Stability studies were carried out on the optimized formulation for a period of 6 months at 40 ± 2°C and 75 ± 5% relative humidity. Pellets with good surface morphology and smooth texture confirmed by stereo micrographs. HMC is easy, efficient, rapid and simple method since virtually no agglomeration seen during coating. In-vitro release from pellets at a given level of coating and for present pellet size was dependent upon the physico-chemical property of the drug and mostly aqueous solubility of the drug. The selection of optimized FF formulation was confirmed by comparing percent cumulative drug release with theoretical release profile. Formulation F2 had difference factor (f 1) and similarity factor (f 2) values was found to be 5 and 66 respectively. F2 showed SR of drug for 8 h with cumulative per cent release of 98.03 ± 4.49%. Release kinetics indicates approximately zero order release pattern. HMC pellets were stable during the course of stability study. By means of HMC using CG and ethyl cellulose, SR pellets containing FF were successfully prepared.

  18. Thermoelectric Properties of Cu-doped Bi2-xSbxTe3 Prepared by Encapsulated Melting and Hot Pressing

    Science.gov (United States)

    Jung, Woo-Jin; Kim, Il-Ho

    2018-03-01

    P-type Bi2-xSbxTe3:Cum (x = 1.5-1.7 and m = 0.002-0.003) solid solutions were synthesized using encapsulated melting and were consolidated using hot pressing. The effects of Sb substitution and Cu doping on the charge transport and thermoelectric properties were examined. The lattice constants decreased with increasing Sb and Cu contents. As the amount of Sb substitution and Cu doping was increased, the electrical conductivity increased, and the Seebeck coefficient decreased owing to the increase in the carrier concentration. All specimens exhibited degenerate semiconductor characteristics and positive Hall and Seebeck coefficients, indicating p-type conduction. The increased Sb substitution caused a shift in the onset temperature of the intrinsic transition and bipolar conduction to higher temperatures. The electronic thermal conductivity increased with increasing Sb and Cu contents owing to the increase in the carrier concentration, while the lattice thermal conductivity slightly decreased due to alloy scattering. A maximum figure of merit, ZTmax = 1.25, was achieved at 373 K for Bi0.4Sb1.6Te3:Cu0.003.

  19. Hot Melt Extruded Amorphous Solid Dispersion of Posaconazole with Improved Bioavailability: Investigating Drug-Polymer Miscibility with Advanced Characterisation

    Directory of Open Access Journals (Sweden)

    Ritesh Fule

    2014-01-01

    Full Text Available Invasive antifungal infections are reasons for morbidity and mortality in immunogenic patients worldwide. Posaconazole is a most promising antifungal agent against all types of invasive infections with high % of cure rate. The marketed suspension formulation has low bioavailability and is needed to be taken with food. In this paper, PCZ hot melt extruded amorphous solid dispersion (SD with immediate release and improved bioavailability was prepared using Soluplus (Sol as primary carrier for solubilization. Surfactants such as PEG 400, Lutrol F27, Lutrol F68, and TPGS are also used in combination with Soluplus to improve the physicochemical performance of the formulation when it comes in contact with GI (gastrointestinal fluid. Drug-polymer miscibility of SD was investigated using advanced techniques. In the in vivo study, the AUC(0–72 and Cmax of PCZ/Soluplus were 11.5 and 11.74 time higher than those of pure PCZ. The formulation of the extrudate SD had an AUC(0–72 and Cmax higher than those with the commercial capsule (Noxafil. Molecular dynamic (MD simulation studies were carried out using in silico molecular modelling to understand the drug-polymer intermolecular behaviour. The results of this research ensure enhanced dissolution and bioavailability of the solid dispersion of PCZ prepared by HME compared with the PCZ suspension.

  20. Effect of low-melting point phases on the microstructure and properties of spark plasma sintered and hot deformed Nd-Fe-B alloys

    Science.gov (United States)

    Zhang, Li; Wang, Meiyu; Yan, Xueliang; Lin, Ye; Shield, Jeffrey

    2018-04-01

    The effect of adding a low melting point Pr-Cu-Al alloy during spark plasma sintering of melt-spun Nd-Fe-B ribbons is investigated. Regions of coarse grains were reduced and overall grain refinement was observed after the addition of Pr68Cu25Al7, leading to an enhancement of coercivity from 12.7 kOe to 20.4 kOe. Hot deformation of the samples in the spark plasma sintering system resulted in the formation of platelet-like grains, producing crystallographic alignment and magnetic anisotropy. The hot deformation process improved the remanence and energy product but reduced the coercivity. The decrease of coercivity resulted from grain growth and aggregation of Pr and Nd elements at triple-junction phases.

  1. Ultrasound-Assist Extrusion Methods for the Fabrication of Polymer Nanocomposites Based on Polypropylene/Multi-Wall Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Carlos A. Ávila-Orta

    2015-11-01

    Full Text Available Isotactic polypropylenes (iPP with different melt flow indexes (MFI were used to fabricate nanocomposites (NCs with 10 wt % loadings of multi-wall carbon nanotubes (MWCNTs using ultrasound-assisted extrusion methods to determine their effect on the morphology, melt flow, and electrical properties of the NCs. Three different types of iPPs were used with MFIs of 2.5, 34 and 1200 g/10 min. Four different NC fabrication methods based on melt extrusion were used. In the first method melt extrusion fabrication without ultrasound assistance was used. In the second and third methods, an ultrasound probe attached to a hot chamber located at the exit of the die was used to subject the sample to fixed frequency and variable frequency, respectively. The fourth method is similar to the first method, with the difference being that the carbon nanotubes were treated in a fluidized air-bed with an ultrasound probe before being used in the fabrication of the NCs with no ultrasound assistance during extrusion. The samples were characterized by MFI, Optical microscopy (OM, Scanning electron microscopy (SEM, Transmission electron microscopy (TEM, electrical surface resistivity, and electric charge. MFI decreases in all cases with addition of MWCNTs with the largest decrease observed for samples with the highest MFI. The surface resistivity, which ranged from 1013 to 105 Ω/sq, and electric charge, were observed to depend on the ultrasound-assisted fabrication method as well as on the melt flow index of the iPP. A relationship between agglomerate size and area ratio with electric charge was found. Several trends in the overall data were identified and are discussed in terms of MFI and the different fabrication methods.

  2. Ultrasound-Assist Extrusion Methods for the Fabrication of Polymer Nanocomposites Based on Polypropylene/Multi-Wall Carbon Nanotubes

    Science.gov (United States)

    Ávila-Orta, Carlos A.; Quiñones-Jurado, Zoe V.; Waldo-Mendoza, Miguel A.; Rivera-Paz, Erika A.; Cruz-Delgado, Víctor J.; Mata-Padilla, José M.; González-Morones, Pablo; Ziolo, Ronald F.

    2015-01-01

    Isotactic polypropylenes (iPP) with different melt flow indexes (MFI) were used to fabricate nanocomposites (NCs) with 10 wt % loadings of multi-wall carbon nanotubes (MWCNTs) using ultrasound-assisted extrusion methods to determine their effect on the morphology, melt flow, and electrical properties of the NCs. Three different types of iPPs were used with MFIs of 2.5, 34 and 1200 g/10 min. Four different NC fabrication methods based on melt extrusion were used. In the first method melt extrusion fabrication without ultrasound assistance was used. In the second and third methods, an ultrasound probe attached to a hot chamber located at the exit of the die was used to subject the sample to fixed frequency and variable frequency, respectively. The fourth method is similar to the first method, with the difference being that the carbon nanotubes were treated in a fluidized air-bed with an ultrasound probe before being used in the fabrication of the NCs with no ultrasound assistance during extrusion. The samples were characterized by MFI, Optical microscopy (OM), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), electrical surface resistivity, and electric charge. MFI decreases in all cases with addition of MWCNTs with the largest decrease observed for samples with the highest MFI. The surface resistivity, which ranged from 1013 to 105 Ω/sq, and electric charge, were observed to depend on the ultrasound-assisted fabrication method as well as on the melt flow index of the iPP. A relationship between agglomerate size and area ratio with electric charge was found. Several trends in the overall data were identified and are discussed in terms of MFI and the different fabrication methods. PMID:28793686

  3. CHARACTERIZATION OF NEW TOOL STEEL FOR ALUMINUM EXTRUSION DIES

    OpenAIRE

    José Britti Bacalhau; Fernanda Moreno Rodrigues; Rafael Agnelli Mesquita

    2014-01-01

    Aluminum extrusion dies are an important segment of application on industrial tools steels, which are manufactured in steels based on AISI H13 steel. The main properties of steels applied to extrusion dies are: wear resistance, impact resistance and tempering resistance. The present work discusses the characteristics of a newly developed hot work steel to be used on aluminum extrusion dies. The effects of Cr and Mo contents with respect to tempering resistance and the Al addition ...

  4. Hot deformed anisotropic nanocrystalline NdFeB based magnets prepared from spark plasma sintered melt spun powders

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Y.H.; Huang, Y.L. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Liu, Z.W., E-mail: zwliu@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Zeng, D.C. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Ma, S.C.; Zhong, Z.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2013-09-01

    Highlights: • Microstructure evolution and its influence on the magnetic properties were investigated. • The increase of stray field and weakening of domain-wall pinning effects were the main reasons of the decrease of the coercivity with increasing the compression ratio. • The influences of non-uniform plastic deformation on the microstructure and magnetic properties were investigated. • Magnetic properties and temperature coefficient of coercivity are indeed very promising without heavy rare earth elements. -- Abstract: Anisotropic magnets were prepared by spark plasma sintering (SPS) followed by hot deformation (HD) using melt-spun powders as the starting material. Good magnetic properties with the remanence J{sub r} > 1.32 T and maximum of energy product (BH){sub max} > 303 kJ/m{sup 3} have been obtained. The microstructure evolution during HD and its influence on the magnetic properties were investigated. The fine grain zone and coarse grain zone formed in the SPS showed different deformation behaviors. The microstructure also had an important effect on the temperature coefficients of coercivity. A strong domain-wall pinning model was valid to interpret the coercivity mechanism of the HDed magnets. The increase of stray field and weakening of domain-wall pinning effects were the main reasons of the decrease of the coercivity with increasing the compression ratio. The influences of non-uniform plastic deformation on the microstructure and magnetic properties were investigated. The polarization characteristics of HDed magnets were demonstrated. It was found out that the HDed magnets had better corrosion resistance than the counterpart sintered magnet.

  5. Evidence for Slab Melt Contributions to the Mexican Volcanic Belt and Other Young Hot Slab Arcs from Lu-Hf Isotopes

    Science.gov (United States)

    Goldstein, S. L.; Cai, Y. M.; Langmuir, C. H.; Lagatta, A.; Straub, S. M.; Gomez-Tuena, A.; Martin Del Pozzo, A.

    2007-12-01

    substantial subducted slab melt contributions to these lavas. Preliminary data from the Colima region in western Mexico also indicate subducted ocean crust melt in stratovolcano lavas. The oceanic crust at the trench near Western and Central Mexico ranges in age from Pliocene to Miocene, thus represents subduction of a young hot slab. The southern Cascades are another case where a young hot slab is being subducted beneath a thick continental crust, and where both calcalkaline and high-Nb alkaline lavas are erupted. These suites show analogous trace element and isotopic relationships to Mexico that delineate contributions from melting of the subducted oceanic crust to the calcalkaline lavas. In contrast, the subducted ocean crust melt signature is absent from western Pacific arcs, where old cold slabs are being subducted, such as the Marianas, New Britain, and Kermedec. Thus the global data thus suggest that Lu- Hf isotopes represent an effective tracer for slab melting, and that young hot slabs melt and old cold slabs don't. We note that our Colima samples are from Jim Luhr, whose interest, enthusiastic support for MVB studies, and generosity are hereby acknowledged and greatly appreciated, and whose scientific counsel is greatly missed.

  6. About the effect of melted zinc mass additives on the formation on layers during hot galvanizing; Zur Wirkung von Zusaetzen zur Zinkschmelze auf die Schichtbildung beim Feuerverzinken

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, P.; Schulz, W.D. [Institut fuer Korrosionsschutz Dresden GmbH, Gostritzer Str. 61-63, D-01217 Dresden (Germany)

    2002-09-01

    The influence of various melted zinc mass additives on the galvanizing behaviour of steels is examined by way of comparison. The mechanisms influencing the formation of layers are very different. In case tin is added, a material barrier of enriched tin develops in the zinc coating, which inhibits the iron transport. The mechanisms of Ni, Ti and Al in the melted zinc mass are explained by means of a new theory on the formation of layers, which is based on the influence of the growth of layers via hydrogen escaping from the steel surface during hot galvanizing. This behaviour makes it clear why the single melted mass additives only have a layer-thickness reducing effect on steels with very definite Si contents. The different inhibitions of the growth of the layer during hot galvanizing are discussed. (Abstract Copyright[2002], Wiley Periodicals, Inc.) [German] Der Einfluss unterschiedlicher Zinkschmelzezusaetze auf das Verzinkungsverhalten der Staehle wird vergleichend untersucht. Die Mechanismen der Einflussnahme auf die Schichtbildung sind sehr unterschiedlich. Bei Zusatz von Zinn entsteht im Zinkueberzug eine Materialbarriere aus angereichertem Zinn, die den Eisentransport hemmt. Die Wirkungsweise von Ni, Ti und Al in der Zinkschmelze wird mit Hilfe einer neuen Theorie der Schichtbildung erklaert. Diese beruht auf der Beeinflussung des Schichtwachstums durch Wasserstoff, der waehrend des Feuerverzinkens aus der Stahloberflaeche austritt. Diese Erklaerung macht verstaendlich, warum die einzelnen Schmelzezusaetze nur bei Staehlen mit ganz bestimmten Si-Gehalten schichtdickenreduzierend wirken. Die unterschiedlichen Hemmungen des Schichtwachstums beim Feuerverzinken werden diskutiert. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

  7. A new method for the continuous production of single dosed controlled release matrix systems based on hot-melt extruded starch: analysis of relevant process parameters and implementation of an in-process control.

    Science.gov (United States)

    Kipping, Thomas; Rein, Hubert

    2013-05-01

    In the present study, we evaluated a novel processing technique for the continuous production of hot-melt extruded controlled release matrix systems. A cutting technique derived from plastics industry, where it is widely used for cutting of cables and wires was adapted into the production line. Extruded strands were shaped by a rotary fly cutter. Special focus is laid on the development of a process analytical technology by evaluating signals obtained from the servo control of the rotary fly cutter. The intention is to provide a better insight into the production process and to offer the ability to detect small variations in process-variables. A co-rotating twin-screw extruder ZSE 27 HP-PH from Leistritz (Nürnberg, Germany) was used to plasticize the starch; critical extrusion parameters were recorded. Still elastic strands were shaped by a rotary fly-cutter type Dynamat 20 from Metzner (Neu-Ulm, Germany). Properties of the final products were analyzed via digital image analysis to point out critical parameters influencing the quality. Important aspects were uniformity of diameter, height, roundness, weight, and variations in the cutting angle. Stability of the products was measured by friability tests and by determining the crushing strength of the final products. Drug loading studies up to 70% were performed to evaluate the capacity of the matrix and to prove the technological feasibility. Changes in viscosities during API addition were analyzed by a Haake Minilab capillary rheometer. X-ray studies were performed to investigate molecular structures of the matrices. External shapes of the products were highly affected by die-swelling of the melt. Reliable reproducibility concerning uniformity of mass could be achieved even for high production rates (>2500cuts/min). Both mechanical strength and die-swelling of the products could be linked to the ratio of amylose to amylopectin. Formulations containing up to 70% of API could still be processed. Viscosity

  8. Influence of Powder Surface Contamination in the Ni-Based Superalloy Alloy718 Fabricated by Selective Laser Melting and Hot Isostatic Pressing

    Directory of Open Access Journals (Sweden)

    Yen-Ling Kuo

    2017-09-01

    Full Text Available The aim of this study was to gain a deep understanding of the microstructure-mechanical relationship between solid-state sintering and full-melting processes. The IN718 superalloy was fabricated by hot isostatic pressing (HIP and selective laser melting (SLM. Continuous precipitates were clearly localized along the prior particle boundary (PPB in the HIP materials, while SLM materials showed a microstructure free of PPB. The mechanical properties of specimens that underwent SLM + solution treatment and aging were comparable to those of conventional wrought specimens both at room temperature and 650 °C. However, a drop was observed in the ductility of HIP material at 650 °C. The brittle particles along the PPB were found to affect the HIP materials’ creep life and ductility during solid-state sintering.

  9. Extrusion product defects: a statistical study

    International Nuclear Information System (INIS)

    Qamar, S.Z.; Arif, A.F.M.; Sheikh, A.K.

    2003-01-01

    In any manufacturing environment, defects resulting in rework or rejection are directly related to product cost and quality, and indirectly linked with process, tooling and product design. An analysis of product defects is therefore integral to any attempt at improving productivity, efficiency and quality. Commercial aluminum extrusion is generally a hot working process and consists of a series of different but integrated operations: billet preheating and sizing, die set and container preheating, billet loading and deformation, product sizing and stretching/roll-correction, age hardening, and painting/anodizing. Product defects can be traced back to problems in billet material and preparation, die and die set design and maintenance, process variable aberrations (ram speed, extrusion pressure, container temperature, etc), and post-extrusion treatment (age hardening, painting/anodizing, etc). The current paper attempts to analyze statistically the product defects commonly encountered in a commercial hot aluminum extrusion setup. Real-world rejection data, covering a period of nine years, has been researched and collected from a local structural aluminum extrusion facility. Rejection probabilities have been calculated for all the defects studied. The nine-year rejection data have been statistically analyzed on the basis of (i) an overall breakdown of defects, (ii) year-wise rejection behavior, (iii) breakdown of defects in each of three cost centers: press, anodizing, and painting. (author)

  10. Hot rolling and annealing effects on the microstructure and mechanical properties of ODS austenitic steel fabricated by electron beam selective melting

    Science.gov (United States)

    Gao, Rui; Ge, Wen-jun; Miao, Shu; Zhang, Tao; Wang, Xian-ping; Fang, Qian-feng

    2016-03-01

    The grain morphology, nano-oxide particles and mechanical properties of oxide dispersion strengthened (ODS)-316L austenitic steel synthesized by electron beam selective melting (EBSM) technique with different post-working processes, were explored in this study. The ODS-316L austenitic steel with superfine nano-sized oxide particles of 30-40 nm exhibits good tensile strength (412 MPa) and large total elongation (about 51%) due to the pinning effect of uniform distributed oxide particles on dislocations. After hot rolling, the specimen exhibits a higher tensile strength of 482 MPa, but the elongation decreases to 31.8% owing to the introduction of high-density dislocations. The subsequent heat treatment eliminates the grain defects induced by hot rolling and increases the randomly orientated grains, which further improves the strength and ductility of EBSM ODS-316L steel.

  11. Coercivity enhancement in hot deformed Nd2Fe14B-type magnets by doping low-melting RCu alloys (R = Nd, Dy, Nd + Dy)

    Science.gov (United States)

    Lee, Y. I.; Huang, G. Y.; Shih, C. W.; Chang, W. C.; Chang, H. W.; You, J. S.

    2017-10-01

    Magnetic properties of the anisotropic NdFeB magnets prepared by hot pressing followed by die-upsetting NdFeB MQU-F powders doped with low-melting RCu alloy powders were explored, where RCu stands for Nd70Cu30, Dy70Cu30 and (Nd0.5Dy0.5)70Cu30, respectively. In addition, the post-annealing at 600 °C was employed to modify the microstructures and the magnetic properties of the hot deformed magnets. It is found that doping RCu alloy powders is effective in enhancing the coercivity of the hot deformed NdFeB magnets from 15.1 kOe to 16.3-19.5 kOe. For Nd70Cu30-doped magnets, the increment of coercivity is only 1.2 kOe. Meanwhile, Dy70Cu30-doped and (Nd0.5Dy0.5)70Cu30-doped magnets show an almost identical enhancement of coercivity of about 4.4 kOe. Importantly, the latter magnet shows a beneficial effect of reducing the usage of Dy from 1.6 wt% to 0.8 wt%. TEM analysis shows that nonmagnetic Nd, Dy and Cu appear at grain boundary and isolate the magnetic grains, leading to an enhancement of coercivity. Doping lower melting point Dy-lean (Nd0.5Dy0.5)70Cu30 powders into commercial MQU-F powders for making high coercivity hot deformed NdFeB magnets might be a potential and economic way for mass production.

  12. Entrapment investigations of water-droplet behavior in a hot tin melt with varying discharge velocities and orifices

    International Nuclear Information System (INIS)

    Froehlich, G.; Mueller, K.

    1983-10-01

    Experiments were performed in which water was pressed through a thermally isolated tube into a clyindrical crucible (diameter 5 cm, height 7,5 cm both measured inside) filled with molten tin (600 K). The diameter of the circular water outlet was varied from 0.5 up to 10 mm and the discharge velocity of the water was in the range of 0.05 up to 20 m/s. In the tin melt the water divides into single drops, which emerged on the melt surface, if an interaction between water and tin melt did not occur. The probability for an interaction increased in experiments with higher discharge velocities of the water and smaller diameters of the water outlet. In experiments with discharge velocities ≥ 5 m/s and outlet diameters ≤ 2 mm one or more interactions occured in each case. At these interactions of water drops entrapped in the tin melt (called entrapment interactions) a portion of the melt was ejected from the crucible. The moment of the interaction and the pulse of the force toward the crucible bottom were recorded. (orig.) [de

  13. Application of rapid solidification powder metallurgy to the fabrication of high-strength, high-ductility Mg-Al-Zn-Ca-La alloy through hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Ayman, Elsayed, E-mail: ayman@jwri.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Junko, Umeda; Katsuyoshi, Kondoh [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2011-01-15

    The microstructure and mechanical properties of hot extruded Mg-7Al-1Zn-1Ca powder alloys with an addition of 1.5% La or 3.3% La were investigated. Both rapidly solidified powders, produced via spinning water atomization process, and cast billets were extruded at 573, 623 and 673 K to optimize the processing conditions for obtaining better mechanical response. Powders were consolidated using both cold compaction and spark plasma sintering. The tensile properties of the extruded alloys were then evaluated and correlated to their microstructures. The results showed that the use of rapidly solidified Mg-7Al-1Zn-1Ca alloy powders with La additions could lead to effective grain refinement and super saturation of alloying elements, which in turn resulted in the improved mechanical response. The Mg-7Al-1Zn-1Ca-1.5La alloy extruded at 573 K attained ultimate tensile strength of 450 {+-} xx MPa and elongation of 17 {+-} xx%, superior to the Mg-7Al-1Zn-1Ca-3.3La alloy and other Mg alloys like Mg-Al-Mn-Ca. This may help extend the application of Mg alloys to higher load-carrying parts while maintaining the excellent advantage of light weight.

  14. Effect of Pre-Oxidation Treatment of Nano-SiC Particulates on Microstructure and Mechanical Properties of SiC/Mg-8Al-1Sn Composites Fabricated by Powder Metallurgy Combined with Hot Extrusion.

    Science.gov (United States)

    Li, Chuan-Peng; Wang, Zhi-Guo; Zha, Min; Wang, Cheng; Yu, Hong-Chen; Wang, Hui-Yuan; Jiang, Qi-Chuan

    2016-11-26

    Nano-SiC particulates (n-SiC p ) reinforced Mg-8Al-1Sn (AT81) composites with different pre-oxidation parameters were fabricated by powder metallurgy (P/M) process combined with hot extrusion. The effects of pre-oxidization treatment of n-SiC p on the microstructure and tensile properties of 0.5 vol % n-SiC p /AT81 composites were investigated accordingly. The distribution of n-SiC p with different pre-oxidation parameters was homogeneous in the composites. Moreover, it was found that a thin MgAl₂O₄ layer formed at the interface when the n-SiC p were pre-oxidized at 1073 K for 2 h, while the MgAl₂O₄ layer became much thicker with pre-oxidization temperature increasing to 1273 K for 2 h. After an appropriate pre-oxidization treatment of n-SiC p at 1073 K for 2 h, the as-extruded 0.5 vol % n-SiC p /AT81 composites exhibited an enhanced strength. It was found that the yield strength (YS) and ultimate tensile strength (UTS) increased from 168 MPa and 311 MPa to 255 MPa and 393 MPa compared with the as-extruded AT81 alloy, reflecting 51.8% and 26.4% increments, respectively. The improvement of mechanical properties should be mainly attributed to the grain refinement and homogeneous distribution of n-SiC p in the composites. Moreover, a well-bonded interface and the formation of an appropriate amount of interfacial product (MgAl₂O₄) benefited the material's mechanical properties.

  15. Improvement of the mechanical properties and corrosion resistance of biodegradable β-Ca3(PO4)2/Mg-Zn composites prepared by powder metallurgy: the adding β-Ca3(PO4)2, hot extrusion and aging treatment.

    Science.gov (United States)

    Yan, Yang; Kang, Yijun; Li, Ding; Yu, Kun; Xiao, Tao; Deng, Youwen; Dai, Han; Dai, Yilong; Xiong, Hanqing; Fang, Hongjie

    2017-05-01

    In this study, 10%β-Ca 3 (PO 4 ) 2 /Mg-6%Zn (wt.%) composites with Mg-6%Zn alloy as control were prepared by powder metallurgy. After hot extrusion, the as-extruded composites were aged for 72h at 150°C. The effects of the adding β-Ca 3 (PO 4 ) 2 , hot extrusion and aging treatment on their microstructure, mechanical properties and corrosion resistance were investigated. The XRD results identified α-Mg, MgZn phase and β-Ca 3 (PO 4 ) 2 phase in these composites. After hot extrusion, grains were significantly refined, and the larger-sized β-Ca 3 (PO 4 ) 2 particles and coarse MgZn phases were broken into linear-distributed β-Ca 3 (PO 4 ) 2 and MgZn phases along the extrusion direction. After aging treatment, the elements of Zn, Ca, P and O presented a more homogeneous distribution. The compressive strengths of the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites were approximately double those of natural bone, and their densities and elastic moduli matched those of natural bone. The immersion tests and electrochemical tests revealed that the adding β-Ca 3 (PO 4 ) 2 , hot extrusion and aging treatment could promote the formation of protective corrosion product layer on the sample surface in Ringer's solution, which improved corrosion resistance of the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites. The XRD results indicated that the corrosion product layer contained Mg(OH) 2 , β-Ca 3 (PO 4 ) 2 and hydroxyapatite (HA). The cytotoxicity assessments showed the as-extruded β-Ca 3 (PO 4 ) 2 /Mg-Zn composite aged for 72h was harmless to L-929 cells. These results suggested that the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites prepared by powder metallurgy were promising to be used for bone tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Towards Extrusion of Ionomers to Process Fuel Cell Membranes

    Directory of Open Access Journals (Sweden)

    Jean-Yves Sanchez

    2011-07-01

    Full Text Available While Proton Exchange Membrane Fuel Cell (PEMFC membranes are currently prepared by film casting, this paper demonstrates the feasibility of extrusion, a solvent-free alternative process. Thanks to water-soluble process-aid plasticizers, duly selected, it was possible to extrude acidic and alkaline polysulfone ionomers. Additionally, the feasibility to extrude composites was demonstrated. The impact of the plasticizers on the melt viscosity was investigated. Following the extrusion, the plasticizers were fully removed in water. The extrusion was found to impact neither on the ionomer chains, nor on the performances of the membrane. This environmentally friendly process was successfully validated for a variety of high performance ionomers.

  17. Numerical studies of temperature effect on the extrusion fracture and swell of plastic micro-pipe

    Science.gov (United States)

    Ren, Zhong; Huang, Xingyuan; Xiong, Zhihua

    2018-03-01

    Temperature is a key factor that impacts extrusion forming quality of plastic micro-pipe. In this study, the effect of temperature on extrusion fracture and swell of plastic micro-pipe was investigated by numerical method. Under a certain of the melt’s flow volume, the extrusion pattern, extrusion swelling ratio of melt are obtained under different temperatures. Results show that the extrusion swelling ratio of plastic micro-pipe decreases with increasing of temperature. In order to study the reason of temperature effect, the physical distributions of plastic micro-pipe are gotten. Numerical results show that the viscosity, pressure, stress value of melt are all decreased with the increasing of temperature, which leads to decrease the extrusion swell and fracture phenomenon for the plastic micro-pipe.

  18. Extrusion Cooking Systems and Textured Vegetable Proteins

    Directory of Open Access Journals (Sweden)

    2015-02-01

    Full Text Available Many fabricated foods are cooked industrially and are given desired textures, shapes, density and rehydration characteristics by an extrusion cooking process. This relatively new process is used in the preparation of “engineered” convenience foods: textured vegetable proteins, breakfast cereals, snacks, infant foods, dry soup mixes, breading, poultry stuffing, croutons, pasta products, beverage powders, hot breakfast gruels, and in the gelatinization of starch or the starchy component of foods.

  19. Powder metallurgy Al–6Cr–2Fe–1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

    International Nuclear Information System (INIS)

    Dám, Karel; Vojtěch, Dalibor; Průša, Filip

    2013-01-01

    Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 °C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 °C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

  20. Powder metallurgy Al-6Cr-2Fe-1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

    Energy Technology Data Exchange (ETDEWEB)

    Dam, Karel, E-mail: Karel.Dam@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Vojtech, Dalibor; Prusa, Filip [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2013-01-10

    Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 Degree-Sign C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 Degree-Sign C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

  1. Coercivity of the Nd–Fe–B hot-deformed magnets diffusion-processed with low melting temperature glass forming alloys

    Energy Technology Data Exchange (ETDEWEB)

    Seelam, U.M.R. [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Liu, Lihua [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Akiya, T.; Sepehri-Amin, H.; Ohkubo, T. [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Sakuma, N.; Yano, M.; Kato, A. [Advanced Material Engineering Division, Toyota Motor Corporation, Susono 410-1193 (Japan); Hono, K., E-mail: kazuhiro.hono@nims.go.jp [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan)

    2016-08-15

    Nd- and Pr-based alloys with bulk glass forming ability and low melting temperatures, Nd{sub 60}Al{sub 10}Ni{sub 10}Cu{sub 20} and Pr{sub 60}Al{sub 10}Ni{sub 10}Cu{sub 20}, were used for grain boundary diffusion process to enhance the coercivity of hot-deformed magnets. The coercivity increment was proportional to the weight gain after the diffusion process. For the sample with 64% weight gain, the coercivity increased up to 2.8 T, which is the highest value for bulk Nd–Fe–B magnets that do not contain heavy rare-earth elements, Dy or Tb. Approximately half of the intergranular regions were amorphous and the remaining regions were crystalline. Magnetic isolation of the Nd{sub 2}Fe{sub 14}B grains by the Nd-rich amorphous/crystalline intergranular phases is attributed to the large coercivity enhancement. The coercivity does not change after the crystallization of the intergranular phase, indicating that the coercivity is not influenced by the strain at the interface with the crystalline intergranular phase. - Highlights: • Bulk-glass forming alloys were infiltrated into hot-deformed Nd–Fe–B magnets. • Very high coercivity of 2.8 T was attained without heavy rare-earth elements. • Approximately half of the inter-granular regions were amorphous. • Crystallization of amorphous intergranular phase does not change coercivity.

  2. Limitations on the Estimation of Parental Magma Temperature Using Olivine-melt Equilibria: Hotspots Not So Hot

    Science.gov (United States)

    Natland, J. H.

    2004-12-01

    Estimates of temperatures of magmas parental to picritic tholeiites using olivine-melt equilibria and FeO-MgO relationships depend strongly on the assumption that a liquid composition, usually a glass, is related to the most magnesian olivine in the rock, or to an olivine composition in equilibrium with mantle peridotite, along an olivine-controlled liquid line of descent. The liquid Fe2+/Fe3+ also has to be known; where data exist, average values from wet chemical determinations are used. Crystallization histories of tholeiitic picrites from islands, spreading ridges, and large igneous provinces, however, usually reveal them to be hybrid rocks that are assembled by two types of magma mixing: 1) between a) differentiated magmas that are on olivine-plagioclase or olivine-plagioclase-clinopyroxene cotectics and b) crystal sludges with abundant olivine that may have accumulated from liquids crystallizing olivine alone; and 2) between primitive magma strains in which olivine crystallized either alone or with other silicate minerals at elevated pressure on separate liquid lines of descent. Many picrites give evidence that both types of mixing have occurred. If either type has occurred, the assumption of olivine-control linking a glass and an olivine composition can only circumstantially be correct. Oxidation state can also be underestimated and therefore FeO contents overestimated if basalts have degassed S, as at Hawaii. In Case 1, hybrid host glass compositions often have higher FeO at given MgO content than liquids which produced many olivine crystals in the rock. In Case 2, the separate parental melt strains are revealed by diversity of compositions of both melt inclusions and Cr-spinel and are most often interpreted to mean local heterogeneity of the mantle source. The inclusions do not always affirm an olivine-controlled liquid line of descent. Instead, inclusions with Gorgona, but not in MORB. Where fresh glass is lacking (e.g., Gorgona), bulk-rock compositions

  3. Functionality of extrusion--texturized whey proteins.

    Science.gov (United States)

    Onwulata, C I; Konstance, R P; Cooke, P H; Farrell, H M

    2003-11-01

    Whey, a byproduct of the cheesemaking process, is concentrated by processors to make whey protein concentrates (WPC) and isolates (WPI). Only 50% of whey proteins are used in foods. In order to increase their usage, texturizing WPC, WPI, and whey albumin is proposed to create ingredients with new functionality. Extrusion processing texturizes globular proteins by shearing and stretching them into aligned or entangled fibrous bundles. In this study, WPC, WPI, and whey albumin were extruded in a twin screw extruder at approximately 38% moisture content (15.2 ml/min, feed rate 25 g/min) and, at different extrusion cook temperatures, at the same temperature for the last four zones before the die (35, 50, 75, and 100 degrees C, respectively). Protein solubility, gelation, foaming, and digestibility were determined in extrudates. Degree of extrusion-induced insolubility (denaturation) or texturization, determined by lack of solubility at pH 7 for WPI, increased from 30 to 60, 85, and 95% for the four temperature conditions 35, 50, 75, and 100 degrees C, respectively. Gel strength of extruded isolates increased initially 115% (35 degrees C) and 145% (50 degrees C), but gel strength was lost at 75 and 100 degrees C. Denaturation at these melt temperatures had minimal effect on foaming and digestibility. Varying extrusion cook temperature allowed a new controlled rate of denaturation, indicating that a texturized ingredient with a predetermined functionality based on degree of denaturation can be created.

  4. Co-extrusion as a processing technique to manufacture a dual sustained release fixed-dose combination product.

    Science.gov (United States)

    Vynckier, An-Katrien; Voorspoels, Jody; Remon, Jean Paul; Vervaet, Chris

    2016-05-01

    This study aimed to design a fixed-dose combination dosage form which provides a sustained release profile for both the freely water-soluble metformin HCl and the poorly soluble gliclazide, two antidiabetic compounds used to treat diabetes mellitus. Hot-melt co-extrusion was used as an innovative manufacturing technique for a pharmaceutical fixed-dose combination product. In this way, a matrix formulation that sustained metformin release could be developed, despite the high drug load in the formulation and the freely soluble nature of the drug. It was clear that co-extrusion was perfectly suited to produce a fixed-dose combination product with adequate properties for each of the incorporated APIs. A coat layer, containing at least 30% CAPA(®) 6506 as a hydrophobic polymer, was necessary to adequately sustain the release of the highly dosed freely soluble drug from the 70% metformin HCl-loaded CAPA(®) 6506 core of the co-extrudate. To obtain a complete gliclazide release over 24-h solubilization in Kollidon(®) VA, added as a second polymer to the CAPA(®) 6506 in the coat, was needed. Both active pharmaceutical ingredients (APIs), which have different physicochemical characteristics, were formulated in a single dosage form, using co-extrusion. © 2016 Royal Pharmaceutical Society, Journal of Pharmacy and Pharmacology.

  5. Microstructural and Microhardness Evolution from Homogenization and Hot Isostatic Pressing on Selective Laser Melted Inconel 718: Structure, Texture, and Phases

    Directory of Open Access Journals (Sweden)

    Raiyan Seede

    2018-05-01

    Full Text Available In this work, the microstructure, texture, phases, and microhardness of 45° printed (with respect to the build direction homogenized, and hot isostatically pressed (HIP cylindrical IN718 specimens are investigated. Phase morphology, grain size, microhardness, and crystallographic texture at the bottom of each specimen differ from those of the top due to changes in cooling rate. High cooling rates during the printing process generated a columnar grain structure parallel to the building direction in the as-printed condition with a texture transition from (001 orientation at the bottom of the specimen to (111 orientation towards the specimen top based on EBSD analysis. A mixed columnar and equiaxed grain structure associated with about a 15% reduction in texture is achieved after homogenization treatment. HIP treatment caused significant grain coarsening, and engendered equiaxed grains with an average diameter of 154.8 µm. These treatments promoted the growth of δ-phase (Ni3Nb and MC-type brittle (Ti, NbC carbides at grain boundaries. Laves phase (Fe2Nb was also observed in the as-printed and homogenized specimens. Ostwald ripening of (Ti, NbC carbides caused excessive grain growth at the bottom of the HIPed IN718 specimens, while smaller grains were observed at their top. Microhardness in the as-fabricated specimens was 236.9 HV and increased in the homogenized specimens by 19.3% to 282.6 HV due to more even distribution of secondary precipitates, and the nucleation of smaller grains. A 36.1% reduction in microhardness to 180.5 HV was found in the HIPed condition due to   γ ″ phase dissolution and differences in grain morphology.

  6. A Look into the Melting Pot: The mecC-Harboring Region Is a Recombination Hot Spot in Staphylococcus stepanovicii.

    Directory of Open Access Journals (Sweden)

    Torsten Semmler

    Full Text Available Horizontal gene transfer (HGT is an important driver for resistance- and virulence factor accumulation in pathogenic bacteria such as Staphylococcus aureus.Here, we have investigated the downstream region of the bacterial chromosomal attachment site (attB for the staphylococcal cassette chromosome mec (SCCmec element of a commensal mecC-positive Staphylococcus stepanovicii strain (IMT28705; ODD4 with respect to genetic composition and indications of HGT. S. stepanovicii IMT28705 was isolated from a fecal sample of a trapped wild bank vole (Myodes glareolus during a screening study (National Network on "Rodent-Borne Pathogens" in Germany. Whole genome sequencing (WGS of IMT28705 together with the mecC-negative type strain CM7717 was conducted in order to comparatively investigate the genomic region downstream of attB (GenBank accession no. KR732654 and KR732653.The bank vole isolate (IMT28705 harbors a mecC gene which shares 99.2% nucleotide (and 98.5% amino acid sequence identity with mecC of MRSA_LGA251. In addition, the mecC-encoding region harbors the typical blaZ-mecC-mecR1-mecI structure, corresponding with the class E mec complex. While the sequences downstream of attB in both S. stepanovicii isolates (IMT28705 and CM7717 are partitioned by 15 bp direct repeats, further comparison revealed a remarkable low concordance of gene content, indicating a chromosomal "hot spot" for foreign DNA integration and exchange.Our data highlight the necessity for further research on transmission routes of resistance encoding factors from the environmental and wildlife resistome.

  7. Friction conditions in the bearing area of an aluminium extrusion process

    NARCIS (Netherlands)

    Ma, X.; de Rooij, Matthias B.; Schipper, Dirk J.

    2012-01-01

    In aluminium extrusion processes, friction inside the bearing channel is important for controlling the surface quality of the extrusion products. The contact materials show a large hardness difference, one being hot aluminium, and the other being hardened tool steel. Further, the contact pressure is

  8. CHARACTERIZATION OF NEW TOOL STEEL FOR ALUMINUM EXTRUSION DIES

    Directory of Open Access Journals (Sweden)

    José Britti Bacalhau

    2014-06-01

    Full Text Available Aluminum extrusion dies are an important segment of application on industrial tools steels, which are manufactured in steels based on AISI H13 steel. The main properties of steels applied to extrusion dies are: wear resistance, impact resistance and tempering resistance. The present work discusses the characteristics of a newly developed hot work steel to be used on aluminum extrusion dies. The effects of Cr and Mo contents with respect to tempering resistance and the Al addition on the nitriding response have been evaluated. From forged steel bars, Charpy impact test and characterization via EPMA have been conducted. The proposed contents of Cr, Mo, and Al have attributed to the new VEX grade a much better tempering resistance than H13, as well as a deeper and harder nitrided layer. Due to the unique characteristics, this new steel provides an interesting alternative to the aluminum extrusion companies to increase their competitiveness.

  9. Embedded Multimaterial Extrusion Bioprinting

    NARCIS (Netherlands)

    Rocca, Marco; Fragasso, Alessio; Liu, Wanjun; Heinrich, Marcel A.; Zhang, Yu Shrike

    Embedded extrusion bioprinting allows for the generation of complex structures that otherwise cannot be achieved with conventional layer-by-layer deposition from the bottom, by overcoming the limits imposed by gravitational force. By taking advantage of a hydrogel bath, serving as a sacrificial

  10. Metal extrusion using hydrostatic pressures

    International Nuclear Information System (INIS)

    Sauve, Ch.

    1965-01-01

    The main problems connected with the deformation of metals due to extrusion are described. A method is put forward for calculating the rational rate of percentage deformation in the case of bar extrusion using a cylindrical container; reference is made to previous work on extrusion using a hydrostatic pressure with or without back-pressure. An extrusion process is described using hydrostatic pressure, without back-pressure, and using the lubricant for transmitting the thrust. This process has been used for eight years by the C.E.A. for the extrusion of a very wide range of metals, from beryllium to uranium and including steels; it leads to excellent surface textures. A very fine crystallization can be obtained on extruded products when the rate of extrusion is very low. There appears to be nothing against the use of high extrusion rates using this method. (author) [fr

  11. High strength Al–Al2O3p composites: Optimization of extrusion parameters

    DEFF Research Database (Denmark)

    Luan, B.F.; Hansen, Niels; Godfrey, A.

    2011-01-01

    Composite aluminium alloys reinforced with Al2O3p particles have been produced by squeeze casting followed by hot extrusion and a precipitation hardening treatment. Good mechanical properties can be achieved, and in this paper we describe an optimization of the key processing parameters...... on an investigation of their mechanical properties and microstructure, as well as on the surface quality of the extruded samples. The evaluation shows that material with good strength, though with limited ductility, can be reliably obtained using a production route of squeeze casting, followed by hot extrusion....... The parameters investigated are the extrusion temperature, the extrusion rate and the extrusion ratio. The materials chosen are AA 2024 and AA 6061, each reinforced with 30vol.% Al2O3 particles of diameter typically in the range from 0.15 to 0.3μm. The extruded composites have been evaluated based...

  12. The positive effect of hot isostatic pressing on improving the anisotropies of bending and impact properties in selective laser melted Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Wu, Ming-Wei; Lai, Pang-Hsin

    2016-01-01

    Selective laser melting (SLM) is a versatile additive manufacturing process for fabricating solid or porous metallic materials with complicated three-dimensional shapes. SLM Ti alloys, particularly Ti-6Al-4V, and other alloys have been manufactured and analyzed in numerous studies. However, the high anisotropy of the microstructures and inconsistent mechanical properties of SLM materials have been extensively reported, and these disadvantages could prohibit its widespread use. To clarify how to alleviate the anisotropic behaviors of SLM materials, the main objective of this study was to evaluate the influences of hot isostatic pressing (HIP) on the microstructure, densification, bending strength, impact toughness, and fracture behavior of the as-built Ti-6Al-4V alloy. The results showed that the vertical and horizontal building directions obviously affect the bending and impact properties of as-built alloys. The transverse rupture strength (TRS) and impact energy of the horizontally-built alloy were respectively found to be 48% and 100% higher than those of the vertically-built one. In the vertically-built alloy, disc-shaped building defects, identified by X-ray computed tomography (CT) and microscopy, obviously reduce the effective load-bearing cross-section and deteriorate the bending and impact performances. After HIP at 1000 °C/150 MPa, the α′-martensite structure in the as-built alloy is transformed into an α+β lamellar one, and the disc-shaped building defects are evidently eliminated. As a result, the impact energies of as-built vertical and horizontal specimens are improved by 28 J (560%) and 19 J (190%), respectively, and the TRS of the as-built vertical alloy is raised by 550 MPa (37%). Consequently, the discrepancies in TRS and impact energy between the HIPed vertical and horizontal specimens are merely 3% and 14%, respectively, and the anisotropic behaviors of the SLM Ti-6Al-4V alloy are thus substantially lessened.

  13. The positive effect of hot isostatic pressing on improving the anisotropies of bending and impact properties in selective laser melted Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ming-Wei, E-mail: mwwu@ntut.edu.tw; Lai, Pang-Hsin

    2016-03-21

    Selective laser melting (SLM) is a versatile additive manufacturing process for fabricating solid or porous metallic materials with complicated three-dimensional shapes. SLM Ti alloys, particularly Ti-6Al-4V, and other alloys have been manufactured and analyzed in numerous studies. However, the high anisotropy of the microstructures and inconsistent mechanical properties of SLM materials have been extensively reported, and these disadvantages could prohibit its widespread use. To clarify how to alleviate the anisotropic behaviors of SLM materials, the main objective of this study was to evaluate the influences of hot isostatic pressing (HIP) on the microstructure, densification, bending strength, impact toughness, and fracture behavior of the as-built Ti-6Al-4V alloy. The results showed that the vertical and horizontal building directions obviously affect the bending and impact properties of as-built alloys. The transverse rupture strength (TRS) and impact energy of the horizontally-built alloy were respectively found to be 48% and 100% higher than those of the vertically-built one. In the vertically-built alloy, disc-shaped building defects, identified by X-ray computed tomography (CT) and microscopy, obviously reduce the effective load-bearing cross-section and deteriorate the bending and impact performances. After HIP at 1000 °C/150 MPa, the α′-martensite structure in the as-built alloy is transformed into an α+β lamellar one, and the disc-shaped building defects are evidently eliminated. As a result, the impact energies of as-built vertical and horizontal specimens are improved by 28 J (560%) and 19 J (190%), respectively, and the TRS of the as-built vertical alloy is raised by 550 MPa (37%). Consequently, the discrepancies in TRS and impact energy between the HIPed vertical and horizontal specimens are merely 3% and 14%, respectively, and the anisotropic behaviors of the SLM Ti-6Al-4V alloy are thus substantially lessened.

  14. Aplicação da técnica de fio quente na determinação das propriedades térmicas de polímeros fundidos Hot wire technique in the determination of thermal properties of melt polymers

    Directory of Open Access Journals (Sweden)

    Wilson N. dos Santos

    2005-11-01

    properties of a material that are needed for heat transfer calculations. Reliable thermal properties values are essential for polymers, both in steady and non-steady state situations. Nowadays, several different techniques for the determination of the thermal diffusivity and thermal conductivity may be found in the literature. In this work, the hot wire parallel technique is employed in the experimental determination of the thermal properties of polymers. Three semi-crystalline polymers (HDPE, LDPE and PP, and two amorphous polymers (PS and HIPS were selected for this work. Samples are prepared through the extrusion process starting from the powder or pellets of the solid polymer. A special mould of stainless steel in the shape of a rectangular parallelepiped provided with ceramic insulators between the hot wire, thermocouple and the mould is employed to store the melt extruded polymer whose thermal properties will be measured. Measurements are carried out from room temperature up to approximately 50 ºC above the melting point. Experimental results obtained are checked against data found in literature and those ones furnished by the manufacturers. A critical analysis of this method shows the advantages and disadvantages of this technique when compared with the laser flash technique.

  15. Microstructural and mechanical properties analysis of an aluminium matrix composite reinforced with the amorphous alloy Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} consolidated by hot extrusion; Propriedades mecanicas e microestruturais de um composito com matrix de aluminio e reforco amorfo de Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} consolidado por extrusao a quente por extrusao a quente

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga, L.C.R.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Peres, M.M., E-mail: peresmm@yahoo.com.b [Universidade Federal de Itajuba (UNIFEI), Itabira, MG (Brazil)

    2010-07-01

    The aim of this work is the microstructure and the mechanical properties analysis of an aluminium matrix composite reinforced with the Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} amorphous alloy. The amorphous alloy was produced by melt-spinning and fragmented in powder particles by milling. Pure aluminium power was moistured with amorphous powder in a proportion of 80:20 (% weight) and processed by milling using 350 rpm during 30 minutes for the generation of a homogeneous composite powder. This product was consolidated by extrusion at 235 deg C, ram speed of 2mm/min and extrusion ratio of 7/1, generating a compact and cylindrical bar with 3 mm of width. The result sample was characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and by X-Ray Diffraction (XRD). Microhardness and compression tests show an improvement on the mechanical properties. (author)

  16. Analysis of Material Flow in Screw Extrusion of Aluminum

    International Nuclear Information System (INIS)

    Haugen, Bjoern; Oernskar, Magnus; Welo, Torgeir; Wideroee, Fredrik

    2010-01-01

    Screw extrusion of aluminum is a new process for production of aluminum profiles. The commercial potential could be large. Little experimental and numerical work has been done with respect to this process.The material flow of hot aluminum in a screw extruder has been analyzed using finite element formulations for the non-Newtonian Navier-Stokes equations. Aluminum material properties are modeled using the Zener-Holloman material model. Effects of stick-slip conditions are investigated with respect to pressure build up and mixing quality of the extrusion process.The numerical results are compared with physical experiments using an experimental screw extruder.

  17. Embedded Multimaterial Extrusion Bioprinting.

    Science.gov (United States)

    Rocca, Marco; Fragasso, Alessio; Liu, Wanjun; Heinrich, Marcel A; Zhang, Yu Shrike

    2018-04-01

    Embedded extrusion bioprinting allows for the generation of complex structures that otherwise cannot be achieved with conventional layer-by-layer deposition from the bottom, by overcoming the limits imposed by gravitational force. By taking advantage of a hydrogel bath, serving as a sacrificial printing environment, it is feasible to extrude a bioink in freeform until the entire structure is deposited and crosslinked. The bioprinted structure can be subsequently released from the supporting hydrogel and used for further applications. Combining this advanced three-dimensional (3D) bioprinting technique with a multimaterial extrusion printhead setup enables the fabrication of complex volumetric structures built from multiple bioinks. The work described in this paper focuses on the optimization of the experimental setup and proposes a workflow to automate the bioprinting process, resulting in a fast and efficient conversion of a virtual 3D model into a physical, extruded structure in freeform using the multimaterial embedded bioprinting system. It is anticipated that further development of this technology will likely lead to widespread applications in areas such as tissue engineering, pharmaceutical testing, and organs-on-chips.

  18. How extrusion shapes food processing

    Science.gov (United States)

    This month's column will explore food extrusion. Extrusion is one of the most commonly used food manufacturing processes. Its versatility enables production of a diverse array of food products. This column will review the basic principles and provide an overview of applications. I would like to ...

  19. Hydrostatic extrusion of magnesium alloys

    NARCIS (Netherlands)

    Sillekens, W.H.; Bohlen, J.

    2012-01-01

    This chapter deals with the capabilities and limitations of the hydrostatic extrusion process for the manufacturing of magnesium alloy sections. Firstly, the process basics for the hydrostatic extrusion of materials in general and of magnesium in particular are introduced. Next, some recent research

  20. High-resolution melting analysis of the single nucleotide polymorphism hot-spot region in the rpoB gene as an indicator of reduced susceptibility to rifaximin in Clostridium difficile.

    Science.gov (United States)

    Pecavar, Verena; Blaschitz, Marion; Hufnagl, Peter; Zeinzinger, Josef; Fiedler, Anita; Allerberger, Franz; Maass, Matthias; Indra, Alexander

    2012-06-01

    Clostridium difficile, a Gram-positive, spore-forming, anaerobic bacterium, is the main causative agent of hospital-acquired diarrhoea worldwide. In addition to metronidazole and vancomycin, rifaximin, a rifamycin derivative, is a promising antibiotic for the treatment of recurring C. difficile infections (CDI). However, exposure of C. difficile to this antibiotic has led to the development of rifaximin-resistance due to point mutations in the β-subunit of the RNA polymerase (rpoB) gene. In the present study, 348 C. difficile strains with known PCR-ribotypes were investigated for respective single nucleotide polymorphisms (SNPs) within the proposed rpoB hot-spot region by using high-resolution melting (HRM) analysis. This method allows the detection of SNPs by comparing the altered melting behaviour of dsDNA with that of wild-type DNA. Discrimination between wild-type and mutant strains was enhanced by creating heteroduplexes by mixing sample DNA with wild-type DNA, leading to characteristic melting curve shapes from samples containing SNPs in the respective rpoB section. In the present study, we were able to identify 16 different rpoB sequence-types (ST) by sequencing analysis of a 325 bp fragment. The 16 PCR STs displayed a total of 24 different SNPs. Fifteen of these 24 SNPs were located within the proposed 151 bp SNP hot-spot region, resulting in 11 different HRM curve profiles (CP). Eleven SNPs (seven of which were within the proposed hot-spot region) led to amino acid substitutions associated with reduced susceptibility to rifaximin and 13 SNPs (eight of which were within the hot-spot region) were synonymous. This investigation clearly demonstrates that HRM analysis of the proposed SNP hot-spot region in the rpoB gene of C. difficile is a fast and cost-effective method for the identification of C. difficile samples with reduced susceptibility to rifaximin and even allows simultaneous SNP subtyping of the respective C. difficile isolates.

  1. Rapid Continuous Multimaterial Extrusion Bioprinting

    NARCIS (Netherlands)

    Liu, Wanjun; Zhang, Yu Shrike; Heinrich, Marcel A.; De Ferrari, F; Jang, HL; Bakht, SM; Alvarez, MM; Yang, J; Li, YC; Trujillo-de Stantiago, G; Miri, AK; Zhu, K; Khoshakhlagh, P; Prakash, G; Cheng, H; Guan, X; Zhong, Z; Ju, J; Zhu, GH; Jin, X; Ryon Shin, Su; Dokmeci, M.R.; Khademhosseini, Ali

    The development of a multimaterial extrusion bioprinting platform is reported. This platform is capable of depositing multiple coded bioinks in a continuous manner with fast and smooth switching among different reservoirs for rapid fabrication of complex constructs, through digitally controlled

  2. Turbine airfoil fabricated from tapered extrusions

    Science.gov (United States)

    Marra, John J

    2013-07-16

    An airfoil (30) and fabrication process for turbine blades with cooling channels (26). Tapered tubes (32A-32D) are bonded together in a parallel sequence, forming a leading edge (21), a trailing edge (22), and pressure and suction side walls (23, 24) connected by internal ribs (25). The tapered tubes may be extruded without camber to simplify the extrusion process, then bonded along matching surfaces (34), forming a non-cambered airfoil (28), which may be cambered in a hot forming process and cut (48) to length. The tubes may have tapered walls that are thinner at the blade tip (T1) than at the base (T2), reducing mass. A cap (50) may be attached to the blade tip. A mounting lug (58) may be forged (60) on the airfoil base and then machined, completing the blade for mounting in a turbine rotor disk.

  3. Investigation of the High-Cycle Fatigue Life of Selective Laser Melted and Hot Isostatically Pressed Ti-6Al-4v

    Science.gov (United States)

    2015-03-26

    marketed for production of parts with metal alloys: electron-beam melting and laser sintering (LS) [3, 10, 36]. The primary distinction between EBM and LS...staircase method described in ASTM STP 588 [68]. The first specimen in a staircase test is tested at a maximum stress level corresponding to the

  4. Microstructure and textural characterization of hot extruded Zr-2.5Nb alloy PHWR pressure tube fabricated by various ingot processing route

    International Nuclear Information System (INIS)

    Vaibhaw, Kumar; Jha, S.K.; Saibaba, N.; Neogy, S.; Mani Krishna, K.V.; Srivastava, D.; Dey, G.K.

    2011-01-01

    Zr-2.5 Nb alloys finds its applications as a pressure tube component in pressure tube type thermal reactors such as PHWRs and RBMK due to properties attributed such as low neutron absorption cross section, high temperature strength and corrosion resistance etc. Manufacturing of this life time components involves series of thermo-mechanical processes of hot working and cold working with intermediate annealing. The life time of Pressure tube are limited due to their diametral creep properties which is governed by metallurgical characteristics such as texture, microstructure dislocation density etc. The primary breakdown of cast structure in Vacuum Arc Melted ingot can be effected by either hot extrusion or forging in single or multiple stages before final hot extrusion step into the blank for manufacturing of seamless pressure tube. Elevated temperature deformation carried out in hot working above the recrystallization temperature would enable impositions of large strains in single step. This deformation causes a significant change in the microstructure of the material and depends on process parameters such as extrusion ratio, temperature and strain rate. Basic microstructure developed at this deformation stage has significant bearing on the final properties of the material fabricated with subsequent cold working steps. The major texture in α+β Zr-2.5 Nb alloy is established during final extrusion to blank which does not change significantly during subsequent cold pilgering. However, microstructure is modified significantly in subsequent cold working which can be effected by cold pilgering or cold drawing in single or multiple steps. Present paper brings out the various ingot processing routes using forging and or extrusion followed for fabrication of pressure tubes. The development of texture and microstructures has been discussed at the blank stage from these processing routes and also with respect to varying extrusion variable such as extrusion ratio

  5. W-Cu composites subjected to heavy hot deformation

    International Nuclear Information System (INIS)

    Yu, Yang; Xu, Xiaoqiang; Zhang, Wencong

    2017-01-01

    The effect of plastic deformation on the properties and microstructure of W-Cu composites produced by multi-pass hot extrusion with steel cup was investigated. W-Cu composites were sintered at 1 100 C and then the sintered billets were firstly extruded at 900 C with different extrusion ratios. The second hot extrusion was performed at 900 C. The plastic deformation of copper phase plays a dominant part during the whole extrusion process. The microstructural evolution of W phase during the whole processing of heavy hot deformation can be divided into different stages. Experimental results indicate that the W agglomeration will be broken into fine particles effectively when the accumulated plastic deformation amounts to 97.6 % after the second extrusion.

  6. W-Cu composites subjected to heavy hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yang; Xu, Xiaoqiang; Zhang, Wencong [Harbin Institute of Technology-Weihai (China). School of Materials Science and Engineering

    2017-04-15

    The effect of plastic deformation on the properties and microstructure of W-Cu composites produced by multi-pass hot extrusion with steel cup was investigated. W-Cu composites were sintered at 1 100 C and then the sintered billets were firstly extruded at 900 C with different extrusion ratios. The second hot extrusion was performed at 900 C. The plastic deformation of copper phase plays a dominant part during the whole extrusion process. The microstructural evolution of W phase during the whole processing of heavy hot deformation can be divided into different stages. Experimental results indicate that the W agglomeration will be broken into fine particles effectively when the accumulated plastic deformation amounts to 97.6 % after the second extrusion.

  7. Morphology and melt rheology of nylon 11/clay nanocomposites

    NARCIS (Netherlands)

    He, Xiaofeng; Yang, Jun; Zhu, Lianchao; Wang, Biao; Sun, Guangping; Lv, Pengfei; Phang, In Yee; Liu, Tianxi

    2006-01-01

    Nylon 11 (PA11)/clay nanocomposites have been prepared by melt-blending, followed by melt-extrusion through a capillary. Transmission electron microscopy shows that the exfoliated clay morphology is dominant for low nanofiller content, while the intercalated one is prevailing for high filler

  8. Identification of non-volatile compounds and their migration from hot melt adhesives used in food packaging materials characterized by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

    Science.gov (United States)

    Vera, Paula; Canellas, Elena; Nerín, Cristina

    2013-05-01

    The identification of unknown non-volatile migrant compounds from adhesives used in food contact materials is a very challenging task because of the number of possible compounds involved, given that adhesives are complex mixtures of chemicals. The use of ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-MS/QTOF) is shown to be a successful tool for identifying non-targeted migrant compounds from two hot melt adhesives used in food packaging laminates. Out of the seven migrants identified and quantified, five were amides and one was a compound classified in Class II of the Cramer toxicity. None of the migration values exceeded the recommended Cramer exposure values.

  9. Machine for extrusion under vacuum

    International Nuclear Information System (INIS)

    Gautier, A.

    1958-01-01

    In a study of the behaviour of easily oxidised metals during the extrusion process, it is first necessary to find an effective mean of fighting corrosion, since this, even when barely detectable, has an important influence on the validity of the results recorded. The neatest and also the most efficient of all the methods tried consists in creating a vacuum around the test piece. Working on this principle, and at the same time respecting the conventional rules for extrusion tests (loading the sample after stabilisation at the testing temperature, differential measurements of lengthening, etc.) we found it necessary to construct an original machine. (author) [fr

  10. Extrusion processing : effects on dry canine diets

    NARCIS (Netherlands)

    Tran, Q.D.

    2008-01-01

    Keywords: Extrusion, Canine diet, Protein, Lysine, Starch gelatinization, Palatability, Drying.

    Extrusion cooking is a useful and economical tool for processing animal feed. This high temperature, short time processing technology causes chemical and physical changes that alter the

  11. Monitoring of polymer melt processing

    International Nuclear Information System (INIS)

    Alig, Ingo; Steinhoff, Bernd; Lellinger, Dirk

    2010-01-01

    The paper reviews the state-of-the-art of in-line and on-line monitoring during polymer melt processing by compounding, extrusion and injection moulding. Different spectroscopic and scattering techniques as well as conductivity and viscosity measurements are reviewed and compared concerning their potential for different process applications. In addition to information on chemical composition and state of the process, the in situ detection of morphology, which is of specific interest for multiphase polymer systems such as polymer composites and polymer blends, is described in detail. For these systems, the product properties strongly depend on the phase or filler morphology created during processing. Examples for optical (UV/vis, NIR) and ultrasonic attenuation spectra recorded during extrusion are given, which were found to be sensitive to the chemical composition as well as to size and degree of dispersion of micro or nanofillers in the polymer matrix. By small-angle light scattering experiments, process-induced structures were detected in blends of incompatible polymers during compounding. Using conductivity measurements during extrusion, the influence of processing conditions on the electrical conductivity of polymer melts with conductive fillers (carbon black or carbon nanotubes) was monitored. (topical review)

  12. The reactive extrusion of thermoplastic polyurethane

    NARCIS (Netherlands)

    Verhoeven, Vincent Wilhelmus Andreas

    2006-01-01

    The objective of this thesis was to increase the understanding of the reactive extrusion of thermoplastic polyurethane. Overall, several issues were identified: • Using a relative simple extrusion model, the reactive extrusion process can be described. This model can be used to further investigate

  13. 75 FR 80527 - Aluminum Extrusions From China

    Science.gov (United States)

    2010-12-22

    ...)] Aluminum Extrusions From China AGENCY: United States International Trade Commission. ACTION: Scheduling of... of subsidized and less-than-fair-value imports from China of aluminum extrusions, primarily provided... contained in Aluminum Extrusions From the People's Republic of China: Notice of Preliminary Determination of...

  14. High resolution melting curve analysis targeting the HBB gene mutational hot-spot offers a reliable screening approach for all common as well as most of the rare beta-globin gene mutations in Bangladesh.

    Science.gov (United States)

    Islam, Md Tarikul; Sarkar, Suprovath Kumar; Sultana, Nusrat; Begum, Mst Noorjahan; Bhuyan, Golam Sarower; Talukder, Shezote; Muraduzzaman, A K M; Alauddin, Md; Islam, Mohammad Sazzadul; Biswas, Pritha Promita; Biswas, Aparna; Qadri, Syeda Kashfi; Shirin, Tahmina; Banu, Bilquis; Sadya, Salma; Hussain, Manzoor; Sarwardi, Golam; Khan, Waqar Ahmed; Mannan, Mohammad Abdul; Shekhar, Hossain Uddin; Chowdhury, Emran Kabir; Sajib, Abu Ashfaqur; Akhteruzzaman, Sharif; Qadri, Syed Saleheen; Qadri, Firdausi; Mannoor, Kaiissar

    2018-01-02

    Bangladesh lies in the global thalassemia belt, which has a defined mutational hot-spot in the beta-globin gene. The high carrier frequencies of beta-thalassemia trait and hemoglobin E-trait in Bangladesh necessitate a reliable DNA-based carrier screening approach that could supplement the use of hematological and electrophoretic indices to overcome the barriers of carrier screening. With this view in mind, the study aimed to establish a high resolution melting (HRM) curve-based rapid and reliable mutation screening method targeting the mutational hot-spot of South Asian and Southeast Asian countries that encompasses exon-1 (c.1 - c.92), intron-1 (c.92 + 1 - c.92 + 130) and a portion of exon-2 (c.93 - c.217) of the HBB gene which harbors more than 95% of mutant alleles responsible for beta-thalassemia in Bangladesh. Our HRM approach could successfully differentiate ten beta-globin gene mutations, namely c.79G > A, c.92 + 5G > C, c.126_129delCTTT, c.27_28insG, c.46delT, c.47G > A, c.92G > C, c.92 + 130G > C, c.126delC and c.135delC in heterozygous states from the wild type alleles, implying the significance of the approach for carrier screening as the first three of these mutations account for ~85% of total mutant alleles in Bangladesh. Moreover, different combinations of compound heterozygous mutations were found to generate melt curves that were distinct from the wild type alleles and from one another. Based on the findings, sixteen reference samples were run in parallel to 41 unknown specimens to perform direct genotyping of the beta-thalassemia specimens using HRM. The HRM-based genotyping of the unknown specimens showed 100% consistency with the sequencing result. Targeting the mutational hot-spot, the HRM approach could be successfully applied for screening of beta-thalassemia carriers in Bangladesh as well as in other countries of South Asia and Southeast Asia. The approach could be a useful supplement of hematological and

  15. Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys

    International Nuclear Information System (INIS)

    Zhang, Erlin; Li, Shengyi; Ren, Jing; Zhang, Lan; Han, Yong

    2016-01-01

    Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti 2 Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti 2 Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (> 99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties. - Highlights: • Hot extrusion refined the grain size and Ti 2 Cu phase significantly. • Hot extrusion increased the mechanical properties and the corrosion resistance. • The antibacterial properties was not affected by the hot process.

  16. Influence of additives on melt viscosity, surface tension, and film formation of dry powder coatings.

    Science.gov (United States)

    Sauer, Dorothea; McGinity, James W

    2009-06-01

    Limited information on thermally cured dry-powder coatings used for solid dosage forms has been available in the literature. The aim of this study was to characterize the film formation process of Eudragit L 100-55 dry-powder coatings and to investigate the influence of film additives on melt viscosity and surface tension. The coating process employed no liquids and the plasticizer was combined with the polymer using hot melt extrusion. Thermoanalytical methods including differential scanning calorimetry and thermogravimetric analysis (TGA) were used to investigate the thermal properties of the dry-coating formulations. The rheological behavior of the coating formulations were characterized with the extrusion torque, and the surface energy parameters were determined from contact angle measurements. The influence of the level of triethyl citrate (TEC) as plasticizer and polyethylene glycol (PEG) 3350 in the polymer film on film formation was investigated using a digital force tester. TGA confirmed thermal stability of all coating excipients at the investigated curing conditions. Increasing TEC levels and the addition of PEG 3350 as a low melting excipient in the coating reduced the viscosity of the polymer. Plasticization of the polymer with TEC increased the surface free energy, whereas the admixture of 10% PEG 3350 did not affect the surface free energy of Eudragit L 100-55. The spreading coefficient of the polymers over two sample tablet formulations was reduced with increasing surface free energy. During the curing process, puncture strength, and elongation of powder-cast films increased. The effect of curing time on the mechanical properties was dependent on the plasticizer content. The incorporation of TEC and PEG 3350 into the Eudragit L 100-55 powder coating formulation improved film formation. Mechanical testing of powder-cast films showed an increase of both elongation and puncture strength over the curing process as criterion for polymer particle fusion

  17. Etching Behavior of Aluminum Alloy Extrusions

    Science.gov (United States)

    Zhu, Hanliang

    2014-11-01

    The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

  18. Effect of extrusion stem speed on extrusion process for a hollow aluminum profile

    International Nuclear Information System (INIS)

    Zhang, Cunsheng; Zhao, Guoqun; Chen, Zhiren; Chen, Hao; Kou, Fujun

    2012-01-01

    Highlights: ► Extrusion stem speed has significant effects on extrusion process. ► An optimum value of stem speed exists for uniform metal flow distribution. ► A higher stem speed leads to a higher required extrusion force. ► A high stem speed leads to an improved welding quality of aluminum profile. - Abstract: Extrusion stem speed is one of important process parameters during aluminum profile extrusion, which directly influences the profile quality and choice of extrusion equipments. In this paper, the extrusion process of a thin-walled hollow aluminum profile was simulated by means of the HyperXtrude commercial software. Through a serial of numerical simulation, the effects of stem speed on extrusion process, such as metal flow behavior at die exit, temperature distribution, extrusion force, and welding pressure, have been investigated. The numerical results showed that there existed an optimum value of stem speed for flow velocity distribution. With the increasing stem speed, the temperature of the extrudate and required extrusion force increased, and the welding quality of extrudate would be improved. Through comprehensive comparison and analysis, the appropriate stem speed could be determined for practical extrusion production. Thus, the research results could give effective guideline for determining initial billet and die temperature and choosing the proper extrusion press in aluminum profile industry.

  19. The extrusion test and sensory perception revisited: Some comments on generality and the effect of measurement temperature.

    Science.gov (United States)

    Brenner, Tom; Tomczyńska-Mleko, Marta; Mleko, Stanisław; Nishinari, Katsuyoshi

    2017-12-01

    Relations between sensory perception, extrusion and fracture in shear, extension and compression are examined. Gelatin-based gels are perceived as less firm and less hard than expected based on their mechanical properties compared to polysaccharide gels that have the same mechanical properties at room temperature but melt well above body temperature, underlying the importance of the measurement temperature for gels that melt during mastication. Correlations between parameters from extrusion and compression, extension and shear are verified using mixed polysaccharide gels. We previously reported a high correlation between several sensory attributes and parameters from an extrusion test. The extrusion test showed the most robust correlation, and could be used to assess samples at both extremes of the texture range with respect to elasticity, for example, both samples that could not be extended as their very low elasticity led to their fracture during handling, as well as samples that could not be fractured in compression. Here, we reexamine the validity of the relations reported. We demonstrate the generality of the relations between large deformation tests and extrusion, but the findings underscore the need to take into account the measurement temperature for samples that melt during mastication when correlating instrumental parameters with sensory perception. © 2017 Wiley Periodicals, Inc.

  20. Development and efficiency assessment of process lubrication for hot forging

    Science.gov (United States)

    Kargin, S.; Artyukh, Viktor; Ignatovich, I.; Dikareva, Varvara

    2017-10-01

    The article considers innovative technologies in testing and production of process lubricants for hot bulk forging. There were developed new compositions of eco-friendly water-graphite process lubricants for hot extrusion and forging. New approaches to efficiency assessment of process lubricants are developed and described in the following article. Laboratory and field results are presented.

  1. Aluminum extrusion with a deformable die

    NARCIS (Netherlands)

    Assaad, W.

    2010-01-01

    Aluminum extrusion process is one of metal forming processes. In aluminum extrusion, a work-piece (billet) is pressed through a die with an opening that closely resembles a desired shape of a profile. By this process, long profiles with an enormous variety of cross-sections can be produced to

  2. Expert system for the optimisation of melt extruded net structures

    CSIR Research Space (South Africa)

    Rawal, A

    2005-01-01

    Full Text Available Net structures were produced by replacing the static die (spinneret) with two concentric dies (consisting of slots) rotating in opposite directions in a melt extrusion process. A series of net structures and filaments were produced from a square die...

  3. Extrusion and drawing of zircaloy 2. Production of pressure tubes for EL-4

    International Nuclear Information System (INIS)

    Thevenet, J.

    1964-01-01

    The authors give briefly the physical mechanical and chemical properties of zircaloy 2, as far as the transformation of this alloy is concerned. Extrusion: After a few general remarks concerning the extrusion and co-extrusion, including a comparison of the deformation resistance of canning metals and of zircaloy 2, the following points are considered: - the difficulties occurring because of the use of this alloy: - atmosphere protection - adjustment on to the machine tools - low thermal conductivity - economy of the metal (price) - the factors affecting the quality of the extruded products extrusion under a copper can and under lubricant glass - fine grain structure - temperature homogeneity - working temperature The transformation cycle - '550 kg ingot - preliminary shape 'for drawing of EL-4 tubes (112 x 120 L 12 m)' - is described in detail (extrusion or forging of the φ = 340 ingot into φ = 220 billets, cutting into lengths and hot drilling at φ = 125, fixing into a copper can and rough extrusion). Drawing: The main difficulties are due to seizing of the tools and to the necessity of protecting the alloy from the atmosphere during annealings. A brief description is given of drawing out on a short mandrel, on a long mandrel, of laminating on a reducing machine and of the carrying out of an annealing, as well as of the production of EL-4 tubes (φ =107 x 113 L 430 m) by drawing out shapes having a size of 112 x 120 on long mandrels. Conclusion: It is possible by extrusion and drawing to produce zircaloy 2 tubes similar to those which may be obtained normally using stainless steel. (authors) [fr

  4. Microstructure and Mechanical Properties of Long Ti-6Al-4V Rods Additively Manufactured by Selective Electron Beam Melting Out of a Deep Powder Bed and the Effect of Subsequent Hot Isostatic Pressing

    Science.gov (United States)

    Lu, S. L.; Tang, H. P.; Ning, Y. P.; Liu, N.; StJohn, D. H.; Qian, M.

    2015-09-01

    An array of eight long Ti-6Al-4V rods (diameter: 12 mm; height: 300 mm) have been additively manufactured, vertically and perpendicular to the powder bed, by selective electron beam melting (SEBM). The purpose was to identify and understand the challenges of fabricating Ti-6Al-4V samples or parts from a deep powder bed (more than 200-mm deep) by SEBM and the necessity of applying post heat treatment. The resulting microstructure and mechanical properties of these Ti-6Al-4V rods were characterized along their building ( i.e., axial) direction by dividing each rod into three segments (top, middle, and bottom), both before ( i.e., as-built) and after hot isostatic pressing (HIP). The as-built microstructure of each rod was inhomogeneous; it was coarsest in the top segment, which showed a near equilibrium α- β lamellar structure, and finest in the bottom segment, which featured a non-equilibrium mixed structure. The tensile properties varied along the rod axis, especially the ductility, but all tensile properties met the requirements specified by ASTM F3001-14. HIP increased the relative density from 99.03 pct of the theoretical density (TD) to 99.90 pct TD and homogenized the microstructure thereby leading to highly consistent tensile properties along the rod axis. The temperature of the stainless steel substrate used in the powder bed was monitored. The as-built inhomogeneous microstructure is attributed to the temperature gradient in the deep powder bed. Post heat treatment is thus necessary for Ti-6Al-4V samples or parts manufactured from a deep powder bed by SEBM. This differs from the additive manufacturing of small samples or parts from a shallow powder bed (less than 100-mm deep) by SEBM.

  5. Development of sustained and dual drug release co-extrusion formulations for individual dosing.

    Science.gov (United States)

    Laukamp, Eva Julia; Vynckier, An-Katrien; Voorspoels, Jody; Thommes, Markus; Breitkreutz, Joerg

    2015-01-01

    In personalized medicine and patient-centered medical treatment individual dosing of medicines is crucial. The Solid Dosage Pen (SDP) allows for an individual dosing of solid drug carriers by cutting them into tablet-like slices. The aim of the present study was the development of sustained release and dual release formulations with carbamazepine (CBZ) via hot-melt co-extrusion for the use in the SDP. The selection of appropriate coat- and core-formulations was performed by adapting the mechanical properties (like tensile strength and E-modulus) for example. By using different excipients (polyethyleneglycols, poloxamers, white wax, stearic acid, and carnauba wax) and drug loadings (30-50%) tailored dissolution kinetics was achieved showing cube root or zero order release mechanisms. Besides a biphasic drug release, the dose-dependent dissolution characteristics of sustained release formulations were minimized by a co-extruded wax-coated formulation. The dissolution profiles of the co-extrudates were confirmed during short term stability study (six months at 21.0 ± 0.2 °C, 45%r.h.). Due to a good layer adhesion of core and coat and adequate mechanical properties (maximum cutting force of 35.8 ± 2.0 N and 26.4 ± 2.8 N and E-modulus of 118.1 ± 8.4 and 33.9 ± 4.5 MPa for the dual drug release and the wax-coated co-extrudates, respectively) cutting off doses via the SDP was precise. While differences of the process parameters (like the barrel temperature) between the core- and the coat-layer resulted in unsatisfying content uniformities for the wax-coated co-extrudates, the content uniformity of the dual drug release co-extrudates was found to be in compliance with pharmacopoeial specification. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Poly(lactic acid) (PLA) Based Tear Resistant and Biodegradable Flexible Films by Blown Film Extrusion

    OpenAIRE

    Norma Mallegni; Thanh Vu Phuong; Maria-Beatrice Coltelli; Patrizia Cinelli; Andrea Lazzeri

    2018-01-01

    Poly(lactic acid) (PLA) was melt mixed in a laboratory extruder with poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) (PBS) in the presence of polypropylene glycol di glycidyl ether (EJ400) that acted as both plasticizer and compatibilizer. The process was then scaled up in a semi-industrial extruder preparing pellets having different content of a nucleating agent (LAK). All of the formulations could be processed by blowing extrusion and the obtained films showed me...

  7. Oriented Structure of Pentablock Copolymers Induced by Solution Extrusion

    Science.gov (United States)

    Harada, Tamotsu; Bates, Frank S.; Lodge, Timothy P.

    2002-03-01

    Highly oriented structure of a poly(styrene-co-butadiene) pentablock copolymer (Mw; 104,700 g/mol, weight percentage of polybutadiene blocks; 29 wt of concentrated solutions. The pentablock copolymer was dissolved into mixtures of toluene and heptane, and the polymer concentration ranged from 40 wt extrusion, the pentablock copolymer was solidified either by coagulation in methanol or by evaporation of the solvent. Interestingly, a highly oriented lamellar structure was confirmed through the small angle X-ray scattering over a specific range of heptane composition, which is a good solvent for polybutadiene, although the hexagonal cylinder morphology was identified for the melt sample. The transition from the oriented lamellar to highly oriented cylinder structure was observed by annealing the samples at temperatures above the glass transition temperature of polystyrene. Moreover, a transition from parallel to perpendicular orientation in the lamellar state was observed with an increase of the extrusion shear rate. A comparison between pentablock and triblock copolymers will be also discussed.

  8. Hot Flashes

    Science.gov (United States)

    Hot flashes Overview Hot flashes are sudden feelings of warmth, which are usually most intense over the face, neck and chest. Your skin might redden, as if you're blushing. Hot flashes can also cause sweating, and if you ...

  9. HOT 2015

    DEFF Research Database (Denmark)

    Hannibal, Sara Stefansen

    2016-01-01

    HOT samler og formidler 21 literacykyndiges bud på, hvad der er hot, og hvad der bør være hot inden for literacy – og deres begrundelser for disse bud.......HOT samler og formidler 21 literacykyndiges bud på, hvad der er hot, og hvad der bør være hot inden for literacy – og deres begrundelser for disse bud....

  10. Evaluation of Extrusion Technique for Nanosizing Liposomes

    Directory of Open Access Journals (Sweden)

    Sandy Gim Ming Ong

    2016-12-01

    Full Text Available The aim of the present study was to study the efficiency of different techniques used for nanosizing liposomes. Further, the aim was also to evaluate the effect of process parameters of extrusion techniques used for nanosizing liposomes on the size and size distribution of the resultant liposomes. To compare the efficiency of different nanosizing techniques, the following techniques were used to nanosize the liposomes: extrusion, ultrasonication, freeze-thaw sonication (FTS, sonication and homogenization. The extrusion technique was found to be the most efficient, followed by FTS, ultrasonication, sonication and homogenization. The extruder used in the present study was fabricated using readily available and relatively inexpensive apparatus. Process parameters were varied in extrusion technique to study their effect on the size and size distribution of extruded liposomes. The results obtained indicated that increase in the flow rate of the extrusion process decreased the size of extruded liposomes however the size homogeneity was negatively impacted. Furthermore, the liposome size and distribution was found to decline with decreasing membrane pore size. It was found that by extruding through a filter with a pore size of 0.2 µm and above, the liposomes produced were smaller than the pore size, whereas, when they were extruded through a filter with a pore size of less than 0.2 µm the resultant liposomes were slightly bigger than the nominal pore size. Besides that, increment of extrusion temperature above transition temperature of the pro-liposome had no effect on the size and size distribution of the extruded liposomes. In conclusion, the extrusion technique was reproducible and effective among all the methods evaluated. Furthermore, processing parameters used in extrusion technique would affect the size and size distribution of liposomes. Therefore, the process parameters need to be optimized to obtain a desirable size range and homogeneity

  11. Extrusion and Extruded Products: Changes in Quality Attributes as Affected by Extrusion Process Parameters: A Review.

    Science.gov (United States)

    Alam, M S; Kaur, Jasmeen; Khaira, Harjot; Gupta, Kalika

    2016-01-01

    Extrusion of foods is an emerging technology for the food industries to process and market a large number of products of varying size, shape, texture, and taste. Extrusion cooking technology has led to production of wide variety of products like pasta, breakfast cereals, bread crumbs, biscuits, crackers, croutons, baby foods, snack foods, confectionery items, chewing gum, texturized vegetable protein (TVP), modified starch, pet foods, dried soups, dry beverage mixes etc. The functional properties of extruded foods plays an important role for their acceptability which include water absorption, water solubility, oil absorption indexes, expansion index, bulk density and viscosity of the dough. The aim of this review is to give the detailed outlines about the potential of extrusion technology in development of different types of products and the role of extrusion-operating conditions and their effect on product development resulting in quality changes i.e physical, chemical, and nutritional, experienced during the extrusion process.

  12. A Novel Continuous Extrusion Process to Fabricate Wedge-Shaped Light Guide Plates

    Directory of Open Access Journals (Sweden)

    Wen-Tse Hsiao

    2013-01-01

    Full Text Available Backlight modules are key components in thin-film transistor liquid crystal displays (TFT-LCD. Among the components of a backlight module, the light guide plate (LGP plays the most important role controlling the light projected to the eyes of users. A wedge-shaped LGP, with its asymmetrical structure, is usually fabricated by an injection proces, but the fabrication time of this process is long. This study proposes a continuous extrusion process to fabricate wedge-shaped LGPs. This continuous process has advantages for mass production. Besides a T-die and rollers, this system also has an in situ monitor of the melt-bank that forms during the extrusion process, helping control the plate thickness. Results show that the melt bank has a close relationship with the plate thickness. The temperature of the bottom heater and roller was adjusted to reduce the surface deformation of the wedge-shaped plate. This continuous extrusion system can successfully manufacture wedge-shaped LGPs for mass production.

  13. Anomalous growth of whisker-like bismuth-tin extrusions from tin-enriched tin-Bi deposits

    International Nuclear Information System (INIS)

    Hu, C.-C.; Tsai, Y.-D.; Lin, C.-C.; Lee, G.-L.; Chen, S.-W.; Lee, T.-C.; Wen, T.-C.

    2009-01-01

    This article shows the first finding that the anomalous growth of Bi-Sn extrusions from tin-enriched alloys (Sn-xBi with x between 20 and 10 wt.%) can be induced by post-plating annealing in N 2 between 145 and 260 deg. C for 10 min although metal whiskers were commonly formed on the surface of pure metals or alloys of the enriched component. From SEM observations, very similar to Sn whiskers, Bi-Sn extrusions vary in size, shape, length, and diameter with changing the annealing temperature, which are highly important in regarding the potential for failure of electronic products. Annealing resulting in thermal expansion of Sn grains is believed to squeeze the Bi-Sn alloys with relatively low melting points to form whisker-like extrusions although the exact mechanism is unclear

  14. Replication of nanopits and nanopillars by roll-to-roll extrusion coating using a structured cooling roll

    DEFF Research Database (Denmark)

    Murthy, Swathi; Pranov, Henrik; Pedersen, Henrik Chresten

    2016-01-01

    This paper investigates a novel, very high throughput, roll-to-roll (R2R) process for nanostructuring of polymer foils, called R2R extrusion coating. It has the potential to accelerate the integration of nanostructured materials in consumer products for a variety of applications, including optical....../height of 100 nm. The best replication was achieved in polypropylene, by running at high roller line-speed of 60 m/min, and high cooling roller temperature of 70°C. Replication in other common polymers like polyethylene and polystyrene was not possible for the parameter range used for the investigation......., technical, and functional surfaces and devices. In roll-to-roll extrusion coating, a molten polymer film is extruded through a flat die forming a melt curtain, and then laminated onto a carrier foil. The lamination occurs as the melt curtain is pressed between a cooling roller and a counter roller...

  15. Towards predictive control of extrusion weld seams: an integrated approach

    NARCIS (Netherlands)

    Bakker, A.J. den; Werkhoven, R.J.; Sillekens, W.H.; Katgerman, L.

    2010-01-01

    Longitudinal weld seams are an intrinsic feature in hollow extrusions produced with porthole dies. The formation of longitudinal weld seams is a solid bonding process, controlled by the local conditions in the extrusion die. Being the weakest areas within the extrusion cross section, it is desirable

  16. Friction phenomena in hydrostatic extrusion of magnesium

    NARCIS (Netherlands)

    Moodij, Ellen

    2014-01-01

    When magnesium is hydrostatically extruded an inconsistent and sometimes bad surface quality is encountered. In hydrostatic extrusion the billet is surrounded by a lubricant, usually castor oil. The required pressure to deform the material is applied onto this lubricant and not directly to the

  17. Root resorption after orthodontic intrusion and extrusion:.

    NARCIS (Netherlands)

    Han, G.; Huang, S.; Hoff, J.W. Von den; Zeng, X.; Kuijpers-Jagtman, A.M.

    2005-01-01

    The aim of this investigation was to compare root resorption in the same individual after application of continuous intrusive and extrusive forces. In nine patients (mean age 15.3 years), the maxillary first premolars were randomly intruded or extruded with a continuous force of 100 cN for eight

  18. Hydrodynamic modelling of hydrostatic magnesium extrusion

    NARCIS (Netherlands)

    Moodij, Ellen; de Rooij, Matthias B.; Schipper, Dirk J.

    2006-01-01

    Wilson’s hydrodynamic model of the hydrostatic extrusion process is extended to meet the geometry found on residual billets. The transition from inlet to work zone of the process is not considered sharp as in the model of Wilson but as a rounded edge, modelled by a parabolic function. It is shown

  19. Extrusion of ECC: Recent Developments and Applications

    DEFF Research Database (Denmark)

    Stang, Henrik; Fredslund-Hansen, Helge; Puclin, Tony

    2008-01-01

    process. Extrusion of cementitious (fiber reinforced) materials has proven particularly difficult due to the high inter-particle friction combined with the disastrous effect of static zones in the flow pattern, and to the ease of phase migration or separation. In order to deal with these conflicting...

  20. Physical and mathematical modelling of extrusion processes

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Gronostajski, Z.; Niechajowics, A.

    2000-01-01

    The main objective of the work is to study the extrusion process using physical modelling and to compare the findings of the study with finite element predictions. The possibilities and advantages of the simultaneous application of both of these methods for the analysis of metal forming processes...

  1. Influence of Extrusion Temperature on the Aging Behavior and Mechanical Properties of an AA6060 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Nadja Berndt

    2018-01-01

    Full Text Available Processing of AA6060 aluminum alloys for semi-products usually includes hot extrusion with subsequent artificial aging for several hours. Processing below the recrystallization temperature allows for an increased strength at a significantly reduced annealing time by combining strain hardening and precipitation hardening. In this study, we investigate the potential of cold and warm extrusion as alternative processing routes for high strength aluminum semi-products. Cast billets of the age hardening aluminum alloy AA6060 were solution annealed and then extruded at room temperature, 120 or 170 °C, followed by an aging treatment. Electron microscopy and mechanical testing were performed on the as-extruded as well as the annealed materials to characterize the resulting microstructural features and mechanical properties. All of the extruded profiles exhibit similar, strongly graded microstructures. The strain gradients and the varying extrusion temperatures lead to different stages of dynamic precipitation in the as-extruded materials, which significantly alter the subsequent aging behavior and mechanical properties. The experimental results demonstrate that extrusion below recrystallization temperature allows for high strength at a massively reduced aging time due to dynamic precipitation and/or accelerated precipitation kinetics. The highest strength and ductility were achieved by extrusion at 120 °C and subsequent short-time aging.

  2. Extrusion of polysaccharide nanocrystal reinforced polymer nanocomposites through compatibilization with poly(ethylene oxide).

    Science.gov (United States)

    Pereda, Mariana; El Kissi, Nadia; Dufresne, Alain

    2014-06-25

    Polysaccharide nanocrystals with a rodlike shape but with different dimensions and specific surface area were prepared from cotton and capim dourado cellulose, and with a plateletlike morphology from waxy maize starch granules. The rheological behavior of aqueous solutions of poly(ethylene oxide) (PEO) with different molecular weights when adding these nanoparticles was investigated evidencing specific interactions between PEO chains and nanocrystals. Because PEO also bears hydrophobic moieties, it was employed as a compatibilizing agent for the melt processing of polymer nanocomposites. The freeze-dried mixtures were used to prepare nanocomposite materials with a low density polyethylene matrix by extrusion. The thermal and mechanical behavior of ensuing nanocomposites was studied.

  3. HOT 2012

    DEFF Research Database (Denmark)

    Lund, Henriette Romme

    Undersøgelse af, hvad der er hot - og hvad der burde være hot på læseområdet med 21 læsekyndige. Undersøgelsen er gennemført siden 2010. HOT-undersøgelsen er foretaget af Nationalt Videncenter for Læsning - Professionshøjskolerne i samarb. med Dansklærerforeningen......Undersøgelse af, hvad der er hot - og hvad der burde være hot på læseområdet med 21 læsekyndige. Undersøgelsen er gennemført siden 2010. HOT-undersøgelsen er foretaget af Nationalt Videncenter for Læsning - Professionshøjskolerne i samarb. med Dansklærerforeningen...

  4. HOT 2014

    DEFF Research Database (Denmark)

    Lund, Henriette

    Undersøgelse af, hvad der er hot - og hvad der burde være hot på læseområdet med 21 læsekyndige. Undersøgelsen er gennemført siden 2010. HOT-undersøgelsen er foretaget af Nationalt Videncenter for Læsning - Professionshøjskolerne i samarb. med Dansklærerforeningen...

  5. HOT 2011

    DEFF Research Database (Denmark)

    Lund, Henriette Romme

    En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager 21 læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet.......En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager 21 læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet....

  6. Improving the automated optimization of profile extrusion dies by applying appropriate optimization areas and strategies

    Science.gov (United States)

    Hopmann, Ch.; Windeck, C.; Kurth, K.; Behr, M.; Siegbert, R.; Elgeti, S.

    2014-05-01

    The rheological design of profile extrusion dies is one of the most challenging tasks in die design. As no analytical solution is available, the quality and the development time for a new design highly depend on the empirical knowledge of the die manufacturer. Usually, prior to start production several time-consuming, iterative running-in trials need to be performed to check the profile accuracy and the die geometry is reworked. An alternative are numerical flow simulations. These simulations enable to calculate the melt flow through a die so that the quality of the flow distribution can be analyzed. The objective of a current research project is to improve the automated optimization of profile extrusion dies. Special emphasis is put on choosing a convenient starting geometry and parameterization, which enable for possible deformations. In this work, three commonly used design features are examined with regard to their influence on the optimization results. Based on the results, a strategy is derived to select the most relevant areas of the flow channels for the optimization. For these characteristic areas recommendations are given concerning an efficient parameterization setup that still enables adequate deformations of the flow channel geometry. Exemplarily, this approach is applied to a L-shaped profile with different wall thicknesses. The die is optimized automatically and simulation results are qualitatively compared with experimental results. Furthermore, the strategy is applied to a complex extrusion die of a floor skirting profile to prove the universal adaptability.

  7. Optical Measurement Technology For Aluminium Extrusions

    International Nuclear Information System (INIS)

    Moe, Per Thomas; Willa-Hansen, Arnfinn; Stoeren, Sigurd

    2007-01-01

    Optical measurement techniques such as laser scanning, structured light scanning and photogrammetry can be used for accurate shape control for aluminum extrusion and downstream processes. The paper presents the fundamentals of optical shape measurement. Furthermore, it focuses on how full-field in- and off-line shape measurement during pure-bending of aluminum extrusions has been performed with stripe projection (structured light) using white light. Full field shape measurement is difficult to implement industrially, but is very useful as a laboratory tool. For example, it has been clearly shown how moderate internal air pressure (less than 5 bars) can significantly reduce undesirable cross-sectional shape distortions during pure bending, and how buckling of the compressive flange occurs at an early stage. Finally, a stretch-bending set-up with adaptive shape control using internal gas pressure and optical techniques is presented

  8. Osmotic mechanism of the loop extrusion process

    Science.gov (United States)

    Yamamoto, Tetsuya; Schiessel, Helmut

    2017-09-01

    The loop extrusion theory assumes that protein factors, such as cohesin rings, act as molecular motors that extrude chromatin loops. However, recent single molecule experiments have shown that cohesin does not show motor activity. To predict the physical mechanism involved in loop extrusion, we here theoretically analyze the dynamics of cohesin rings on a loop, where a cohesin loader is in the middle and unloaders at the ends. Cohesin monomers bind to the loader rather frequently and cohesin dimers bind to this site only occasionally. Our theory predicts that a cohesin dimer extrudes loops by the osmotic pressure of cohesin monomers on the chromatin fiber between the two connected rings. With this mechanism, the frequency of the interactions between chromatin segments depends on the loading and unloading rates of dimers at the corresponding sites.

  9. Deformations in micro extrusion of metals

    Directory of Open Access Journals (Sweden)

    J. Piwnik

    2010-07-01

    Full Text Available Production technologies of small dimensions metallic elements are known for a long time. They are produced by machining methods:turning, milling, polishing. Recently, methods for manufacturing small details by forming are developed – microforming. This process ischaracterized by the high dimensions accuracy and the surface smoothness of received items and the high production rate. When a forming process is scaled down to micro dimensions, the microstructure of the workpiece, the surface topology of the workpiece and that of the tooling remain unchanged. Size effect is appearing. This paper analyses specifications of a metal extrusion in micro scale. To determine the impact of the tool surface roughness on deformation process the numerical model of roughness as triangle wave were developed. In paper the influence of the wave presence on the material flow is described. Impact of the forming conditions on extrusion forces there is also characterized.

  10. Die design and process optimization of plastic gear extrusion

    Science.gov (United States)

    Zhang, Lei; Fu, Zhihong; Yao, Chen; Zang, Gongzheng; Wan, Yue

    2018-01-01

    The flow velocity of the melt in the extruder was simulated by using software Polyflow, and the size of the die channel with the best flow uniformity was obtained. The die profile shape is obtained by reverse design. The length of the shaping section is determined by Ansys transient thermal analysis. According to the simulation results, the design and manufacture of extrusion die of plastic gear and vacuum cooling setting were obtained. The influence of the five process parameters on the precision of the plastic gear were studied by the single factor analysis method, such as the die temperature T, the screw speed R, the die spacing S, the vacuum degree M and the hauling speed V. The optimal combination of process parameters was obtained by using the neural network particle swarm optimization algorithm(T = 197.05 °C, R = 9.04rpm, S = 67mm, M = -0.0194MPa). The tooth profile deviation of the extruded plastic gear can reach 9 level of accuracy.

  11. Back extrusion of vocadlo-type fluids

    Czech Academy of Sciences Publication Activity Database

    David, Jiří; Filip, Petr; Kharlamov, Alexander

    2013-01-01

    Roč. 23, č. 4 (2013), , 45366-1-45366-8 ISSN 1430-6395 R&D Projects: GA ČR GA103/09/2066 Institutional support: RVO:67985874 Keywords : viscosity * back extrusion * annular pumping * vocadlo model * Robertson-stiff model Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.592, year: 2013 http://www.ar.ethz.ch/TMPPDF/23840225602.368/ApplRheol_23_45366.pdf

  12. Bibliography of ceramic extrusion and plasticity

    Energy Technology Data Exchange (ETDEWEB)

    Janney, M.A.; Vance, M.C.; Jordan, A.C.; Kertesz, M.P.

    1987-03-01

    A comprehensive bibliography of ceramic extrusion and plasticity has been compiled. Over 670 abstracts are included covering the period 1932 to 1984. Citations cover a wide range of interests from basic science investigations to engineering ''tips'' and include references to brick and tile, whitewares, technical ceramics, theoretical models, engineering analyses, forming, drying, and raw materials. In addition to the citations, there are numerous indices to make the bibliography easy to use.

  13. Effect of extrusion temperature and moisture content of corn flour on crystallinity and hardness of rice analogues

    Science.gov (United States)

    Budi, Faleh Setia; Hariyadi, Purwiyatno; Budijanto, Slamet; Syah, Dahrul

    2015-12-01

    Rice analogues are food products made of broken rice and/or any other carbohydrate sources to have similar texture and shape as rice. They are usually made by hot extrusion processing. The hot extrusion process may change the crystallinity of starch and influence the characteristic of rice analogues. Therefore, this research aimed to study the effect of moisture content of incoming dough and temperature of extrusion process on the crystallinity and hardness of resulting rice analogues. The dough's were prepared by mixing of corn starch-flour with ratio 10/90 (w/w) and moisture content of 35%, 40% and 45% (w/w) and extrusion process were done at temperature of 70, 80, 90°C by using of twin screw extruder BEX-DS-2256 Berto. The analyses were done to determine the type of crystal, degree of crystallinity, and hardness of the resulting rice analogues. Our result showed that the enhancement of extrusion temperature from 70 - 90°C increased degree of crystallinity from 5.86 - 15.00% to 10.70 - 18.87% and hardness from 1.71 - 4.36 kg to 2.05 - 5.70 kg. The raising of dough moisture content from 35 - 45% decreased degree of crystallinity from 15.00 - 18.87% to 5.86 - 10.70% and hardness from 4.36 - 5.70 kg to 1.71 - 2.05 kg. The increase of degree of crystallinity correlated positively with the increase of hardness of rice analogues (r = 0.746, p = 0.05).

  14. Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys.

    Science.gov (United States)

    Zhang, Erlin; Li, Shengyi; Ren, Jing; Zhang, Lan; Han, Yong

    2016-12-01

    Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti2Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti2Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (>99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Friction measurement and modelling in forward rod extrusion

    DEFF Research Database (Denmark)

    Tan, Xincai; Bay, Niels; Zhang, Wenqi

    2003-01-01

    Forward extrusion is one of the important processes in bulk metal forming. Friction stress can be estimated from the slope of the load±displacement curve at the steady state after the maximum load in a forward extrusion test. In this paper, forward rod extrusion tests are carried out to determine...... as the lubricant. Friction stresses are obtained from measurements of slopes of extrusion pressure±punch travel curves at the steady state stage. Normal pressures are evaluated by using Mohr’s circle, in which shear ¯ow stresses are estimated at the maximum elastic deformation points from the same extrusion...... pressure±punch travel curves. It is found that the relationship between normal pressure and friction stress appears linear, and therefore Coulomb’s friction model ®ts the experimental data very well. Extrusion pressure±punch travel curves before the steady state can be divided into four stages: elastic...

  16. Process Parameter Optimization of Extrusion-Based 3D Metal Printing Utilizing PW–LDPE–SA Binder System

    Directory of Open Access Journals (Sweden)

    Luquan Ren

    2017-03-01

    Full Text Available Recently, with a broadening range of available materials and alteration of feeding processes, several extrusion-based 3D printing processes for metal materials have been developed. An emerging process is applicable for the fabrication of metal parts into electronics and composites. In this paper, some critical parameters of extrusion-based 3D printing processes were optimized by a series of experiments with a melting extrusion printer. The raw materials were copper powder and a thermoplastic organic binder system and the system included paraffin wax, low density polyethylene, and stearic acid (PW–LDPE–SA. The homogeneity and rheological behaviour of the raw materials, the strength of the green samples, and the hardness of the sintered samples were investigated. Moreover, the printing and sintering parameters were optimized with an orthogonal design method. The influence factors in regard to the ultimate tensile strength of the green samples can be described as follows: infill degree > raster angle > layer thickness. As for the sintering process, the major factor on hardness is sintering temperature, followed by holding time and heating rate. The highest hardness of the sintered samples was very close to the average hardness of commercially pure copper material. Generally, the extrusion-based printing process for producing metal materials is a promising strategy because it has some advantages over traditional approaches for cost, efficiency, and simplicity.

  17. Process Parameter Optimization of Extrusion-Based 3D Metal Printing Utilizing PW–LDPE–SA Binder System

    Science.gov (United States)

    Ren, Luquan; Zhou, Xueli; Song, Zhengyi; Zhao, Che; Liu, Qingping; Xue, Jingze; Li, Xiujuan

    2017-01-01

    Recently, with a broadening range of available materials and alteration of feeding processes, several extrusion-based 3D printing processes for metal materials have been developed. An emerging process is applicable for the fabrication of metal parts into electronics and composites. In this paper, some critical parameters of extrusion-based 3D printing processes were optimized by a series of experiments with a melting extrusion printer. The raw materials were copper powder and a thermoplastic organic binder system and the system included paraffin wax, low density polyethylene, and stearic acid (PW–LDPE–SA). The homogeneity and rheological behaviour of the raw materials, the strength of the green samples, and the hardness of the sintered samples were investigated. Moreover, the printing and sintering parameters were optimized with an orthogonal design method. The influence factors in regard to the ultimate tensile strength of the green samples can be described as follows: infill degree > raster angle > layer thickness. As for the sintering process, the major factor on hardness is sintering temperature, followed by holding time and heating rate. The highest hardness of the sintered samples was very close to the average hardness of commercially pure copper material. Generally, the extrusion-based printing process for producing metal materials is a promising strategy because it has some advantages over traditional approaches for cost, efficiency, and simplicity. PMID:28772665

  18. Process Parameter Optimization of Extrusion-Based 3D Metal Printing Utilizing PW-LDPE-SA Binder System.

    Science.gov (United States)

    Ren, Luquan; Zhou, Xueli; Song, Zhengyi; Zhao, Che; Liu, Qingping; Xue, Jingze; Li, Xiujuan

    2017-03-16

    Recently, with a broadening range of available materials and alteration of feeding processes, several extrusion-based 3D printing processes for metal materials have been developed. An emerging process is applicable for the fabrication of metal parts into electronics and composites. In this paper, some critical parameters of extrusion-based 3D printing processes were optimized by a series of experiments with a melting extrusion printer. The raw materials were copper powder and a thermoplastic organic binder system and the system included paraffin wax, low density polyethylene, and stearic acid (PW-LDPE-SA). The homogeneity and rheological behaviour of the raw materials, the strength of the green samples, and the hardness of the sintered samples were investigated. Moreover, the printing and sintering parameters were optimized with an orthogonal design method. The influence factors in regard to the ultimate tensile strength of the green samples can be described as follows: infill degree > raster angle > layer thickness. As for the sintering process, the major factor on hardness is sintering temperature, followed by holding time and heating rate. The highest hardness of the sintered samples was very close to the average hardness of commercially pure copper material. Generally, the extrusion-based printing process for producing metal materials is a promising strategy because it has some advantages over traditional approaches for cost, efficiency, and simplicity.

  19. Keweenaw hot spot: Geophysical evidence for a 1.1 Ga mantle plume beneath the Midcontinent Rift System

    Science.gov (United States)

    Hutchinson, D.R.; White, R.S.; Cannon, W.F.; Schulz, K.J.

    1990-01-01

    The Proterozoic Midcontinent Rift System of North America is remarkably similar to Phanerozoic rifted continental margins and flood basalt provinces. Like the younger analogues, the volcanism within this older rift can be explained by decompression melting and rapid extrusion of igneous material during lithospheric extension above a broad, asthenospheric, thermal anomaly which we call the Keweenaw hot spot. Great Lakes International Multidisciplinary Program on Crustal Evolution seismic reflection profiles constrain end-member models of melt thickness and stretching factors, which yield an inferred mantle potential temperature of 1500°–1570°C during rifting. Combined gravity modeling and subsidence calculations are consistent with stretching factors that reached 3 or 4 before rifting ceased, and much of the lower crust beneath the rift consists of relatively high density intruded or underplated synrift igneous material. The isotopic signature of Keweenawan volcanic rocks, presented in a companion paper by Nicholson and Shirey (this issue), is consistent with our model of passive rifting above an asthenospheric mantle plume.

  20. Zr Extrusion – Direct Input for Models & Validation

    Energy Technology Data Exchange (ETDEWEB)

    Cerreta, Ellen Kathleen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-07

    As we examine differences in the high strain rate, high strain tensile response of high purity, highly textured Zr as a function of loading direction, temperature and extrusion velocity with primarily post mortem characterization techniques, we have also developed a technique for characterizing the in-situ extrusion process. This particular measurement is useful for partitioning energy of the system during the extrusion process: friction, kinetic energy, and temperature

  1. Studies in reactive extrusion processing of biodegradable polymeric materials

    Science.gov (United States)

    Balakrishnan, Sunder

    Various reaction chemistries such as Polymerization, Polymer cross-linking and Reactive grafting were investigated in twin-screw extruders. Poly (1,4-dioxan-2-one) (PPDX) was manufactured in melt by the continuous polymerization of 1,4-dioxan-2-one (PDX) monomer in a twin-screw extruder using Aluminum tri-sec butoxide (ATSB) initiator. Good and accurate control over molecular weight was obtained by controlling the ratio of monomer to initiator. A screw configuration consisting of only conveying elements was used for the polymerization. The polymerization reaction was characterized by a monomer-polymer dynamic equilibrium, above the melting temperature of the polymer, limiting the equilibrium conversion to 78-percent. Near complete (˜100-percent) conversion was obtained on co-polymerizing PDX monomer with a few mol-percent (around 8-percent) Caprolactone (CL) monomer in a twin-screw extruder using ATSB initiator. The co-polymers exhibited improved thermal stability with reduction in glass transition temperature. The extruder was modeled as an Axial Dispersed Plug Flow Reactor for the polymerization of CL monomer using Residence Time Distribution (RTD) Analysis. The model provided a good fit to the experimental RTD and conversion data. Aliphatic and aliphatic-aromatic co-polyesters, namely Polycaprolactone (PCL) and Poly butylenes (adipate-co-terephthalate) (Ecoflex) were cross-linked in a twin-screw extruder using radical initiator to form micro-gel reinforced biodegradable polyesters. Cross-linked Ecoflex was further extrusion blended with talc to form blends suitable to be blown into films. A screw configuration consisting of conveying and kneading elements was found to be effective in dispersion of the talc particles (5--10 microns) in the polyester matrix. While the rates of crystallization increased for the talc filled polyester blends, overall crystallinity reduced. Mechanical, tear and puncture properties of films made using the talc filled polyester blends

  2. Lithosphere destabilization by melt percolation during pre-oceanic rifting: Evidence from Alpine-Apennine ophiolitic peridotites

    Science.gov (United States)

    Piccardo, Giovanni; Ranalli, Giorgio

    2017-04-01

    conditions. This indicates that thermal advection by percolation of hot asthenospheric melts significantly heated the lithospheric mantle column above the melting asthenosphere. Numerical and analogue models show that infiltration of melts results in considerable softening of mantle rocks. Total ithospheric strength can be decreased from 10 to 1 TN m-1 as orders of magnitude and the sin-rift thermo-mechanical erosion of the lithospheric mantle induces significant rheological softening along the axial zone of extension (Corti et al., 2007; Ranalli et al., 2007). Softening of the lithospheric mantle may lead to whole lithospheric failure and consequently to transition from continental extension to oceanic spreading. Therefore, rheological softening caused destabilization of the lithospheric mantle between the future continental margins (Piccardo et al., 2014; Piccardo, 2016) of the Ligurian Tethys. The wedge of destabilized lithosphere favored faster divergence of the continental blocks and enhanced doming and thermal buoyancy of deeper/hotter asthenosphere that rose between the future continental margins and originated aggregated MORB melts (i.e., the oceanic magmatism that formed olivine-gabbro intrusions and pillowed basalt extrusions). Lithosphere destabilization by melt percolation can play a fundamental role in the geodynamic evolution of lithosphere extension causing transition from continental extension to continental break-up to oceanic spreading. Corti, G., Bonini, M., Innocenti, F., Manetti, P., Piccardo, G.B., Ranalli, G., 2007. Journal of Geodynamics, 43, 465-483. Piccardo, G.B., Padovano, M., Guarnieri, L. 2014. Earth-Science Reviews, 138, 409-434. Piccardo, G.B., 2016. Gondwana Research, 39, 230-249. Piccardo, G.B., Vissers, R.L.M., 2007. Journal of Geodynamics, 43, 417-449. Piccardo, G.B., Guarnieri, L., 2011. Lithos, 124, 210-214. Ranalli, G., Piccardo, G.B., Corona-Chavez, P., 2007. Journal of Geodynamics, 43, 450-464.

  3. MODERNIZATION OF TECHNOLOGICAL LINE FOR CELLULAR EXTRUSION PROCESS

    Directory of Open Access Journals (Sweden)

    Tomasz Garbacz

    2014-06-01

    As part of the modernization of the cellular extrusion technology the extrusion head was designed and made. During the designing and modeling of the head the Auto CAD programe was used. After the prototyping the extrusion head was tested. In the article specification of cellular extrusion process of thermoplastics was presented. In the research, the endothermal chemical blowing agents in amount 1,0% by mass were used. The quantity of used blowing agent has a direct influence on density and structure of the extruded product of modified polymers. However, these properties have further influence on porosity, impact strength, hardness, tensile strength and another.

  4. HOT 2010

    DEFF Research Database (Denmark)

    Lund, Henriette Romme

    En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager en række læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet. Undersøgelsen er gentaget hvert år siden 2010.......En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager en række læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet. Undersøgelsen er gentaget hvert år siden 2010....

  5. HOT 2013

    DEFF Research Database (Denmark)

    Lund, Henriette Romme

    En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager en række læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet. Undersøgelsen er gentaget hvert år siden 2010.......En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager en række læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet. Undersøgelsen er gentaget hvert år siden 2010....

  6. Microstructure Evolution in Mg-Zn-Zr-Gd Biodegradable Alloy: The Decisive Bridge Between Extrusion Temperature and Performance.

    Science.gov (United States)

    Yao, Huai; Wen, Jiu-Ba; Xiong, Yi; Lu, Yan; Huttula, Marko

    2018-01-01

    Being a biocompatible metal with similar mechanical properties as bones, magnesium bears both biodegradability suitable for bone substitution and chemical reactivity detrimental in bio-ambiences. To benefit its biomaterial applications, we developed Mg-2.0Zn-0.5Zr-3.0Gd (wt%) alloy through hot extrusion and tailored its biodegradability by just varying the extrusion temperatures during alloy preparations. The as-cast alloy is composed of the α-Mg matrix, a network of the fish-bone shaped and ellipsoidal (Mg, Zn) 3 Gd phase, and a lamellar long period stacking ordered phase. Surface content of dynamically recrystallized (DRXed) and large deformed grains increases within 330-350°C of the extrusion temperature, and decreases within 350-370°C. Sample second phase contains the (Mg, Zn) 3 Gd nano-rods parallel to the extrusion direction, and Mg 2 Zn 11 nanoprecipitation when temperature tuned above 350°C. Refining microstructures leads to different anticorrosive ability of the alloys as given by immersion and electrochemical corrosion tests in the simulated body fluids. The sample extruded at 350°C owns the best anticorrosive ability thanks to structural impacts where large DRXed portions and uniform nanosized grains reduce chemical potentials among composites, and passivate the extruded surfaces. Besides materials applications, the in vitro mechanism revealed here is hoped to inspire similar researches in biometal developments.

  7. Microstructure evolution in Mg-Zn-Zr-Gd biodegradable alloy: the decisive bridge between extrusion temperature and performance

    Science.gov (United States)

    Yao, Huai; Wen, Jiu-Ba; Xiong, Yi; Lu, Yan; Huttula, Marko

    2018-03-01

    Being a biocompatible metal with similar mechanical properties as bones, magnesium bears both biodegradability suitable for bone substitution and chemical reactivity detrimental in bio-ambiences. To benefit its biomaterial applications, we developed Mg-2.0Zn-0.5Zr-3.0Gd (wt%) alloy through hot extrusion and tailored its biodegradability by just varying the extrusion temperatures during alloy preparations. The as-cast alloy is composed of the α-Mg matrix, a network of the fish-bone shaped and ellipsoidal (Mg, Zn)3Gd phase, and a lamellar long period stacking ordered phase. Surface content of dynamically recrystallized (DRXed) and large deformed grains increases within 330-350 C of the extrusion temperature, and decreases within 350-370 C. Sample second phase contains the (Mg, Zn)3Gd nano-rods parallel to the extrusion direction, and Mg2Zn11 nanoprecipitation when temperature tuned above 350 C. Refining microstructures leads to different anticorrosive ability of the alloys as given by immersion and electrochemical corrosion tests in the simulated body fluids. The sample extruded at 350 C owns the best anticorrosive ability thanks to structural impacts where large DRXed portions and uniform nanosized grains reduce chemical potentials among composites, and passivate the extruded surfaces. Besides materials applications, the in vitro mechanism revealed here is hoped to inspire similar researches in biometal developments.

  8. Microstructure Evolution in Mg-Zn-Zr-Gd Biodegradable Alloy: The Decisive Bridge Between Extrusion Temperature and Performance

    Directory of Open Access Journals (Sweden)

    Huai Yao

    2018-03-01

    Full Text Available Being a biocompatible metal with similar mechanical properties as bones, magnesium bears both biodegradability suitable for bone substitution and chemical reactivity detrimental in bio-ambiences. To benefit its biomaterial applications, we developed Mg-2.0Zn-0.5Zr-3.0Gd (wt% alloy through hot extrusion and tailored its biodegradability by just varying the extrusion temperatures during alloy preparations. The as-cast alloy is composed of the α-Mg matrix, a network of the fish-bone shaped and ellipsoidal (Mg, Zn3Gd phase, and a lamellar long period stacking ordered phase. Surface content of dynamically recrystallized (DRXed and large deformed grains increases within 330–350°C of the extrusion temperature, and decreases within 350–370°C. Sample second phase contains the (Mg, Zn3Gd nano-rods parallel to the extrusion direction, and Mg2Zn11 nanoprecipitation when temperature tuned above 350°C. Refining microstructures leads to different anticorrosive ability of the alloys as given by immersion and electrochemical corrosion tests in the simulated body fluids. The sample extruded at 350°C owns the best anticorrosive ability thanks to structural impacts where large DRXed portions and uniform nanosized grains reduce chemical potentials among composites, and passivate the extruded surfaces. Besides materials applications, the in vitro mechanism revealed here is hoped to inspire similar researches in biometal developments.

  9. Expansion of the whole wheat flour extrusion

    DEFF Research Database (Denmark)

    Cheng, Hongyuan; Friis, Alan

    2008-01-01

    A new model framework is proposed to describe the expansion of extrudates with extruder operating conditions based on dimensional analysis principle. The Buckingham pi dimensional analysis method is applied to form the basic structure of the model from extrusion process operational parameters. Us....... Using the Central Composite Design (CCD) method, whole wheat flour was processed in a twin-screw extruder with 16 trials. The proposed model can well correlate the expansion of the 16 trials using 3 regression parameters. The average deviation of the correlation is 5.9%....

  10. Limits of Lubrication in Backward Can Extrusion

    DEFF Research Database (Denmark)

    Bennani, B; Bay, Niels

    1996-01-01

    The increasing demand in industry to produce cans at low reduction by the backward extrusion process involves better understanding of this process. To analyse the process, numerical simulations by the finite-element method and experimental simulations by physical modelling using wax as a model...... on the reduction, the punch geometry, the workpiece material and the friction factor, in order to avoid the risk of damage caused by stiction of the workpiece material to the punch face. The influence of these different parameters on the distribution of the surface expansion along the inner can wall and bottom...... is determined. The numerical and experimental simulations showed good accordance....

  11. Meltlets(®) of soy isoflavones: process optimization and the effect of extrusion spheronization process parameters on antioxidant activity.

    Science.gov (United States)

    Deshmukh, Ketkee; Amin, Purnima

    2013-07-01

    In the current research work an attempt was made to develop "Melt in mouth pellets" (Meltlets(®)) containing 40% herbal extract of soy isoflavones that served to provide antioxidants activity in menopausal women. The process of extrusion-spheronization was optimized for extruder speed, extruder screen size, spheronization speed, and time. While doing so the herbal extract incorporated in the pellet matrix was subjected to various processing conditions such as the effect of the presence of other excipients, mixing or kneading to prepare wet mass, heat generated during the process of extrusion, spheronization, and drying. Thus, the work further investigates the effect of these processing parameters on the antioxidant activity of the soy isoflavone herbal extract incorporated in the formula. Thereby, the antioxidant activity of the soya bean herbal extract, Meltlets(®) and of the placebo pellets was evaluated using DPPH free radical scavenging assay and total reduction capacity.

  12. Influence of material and solution composition on the extrusion/erosion behaviour of compacted bentonite

    International Nuclear Information System (INIS)

    Schatz, Timothy; Martikainen, Jari; Koskinen, Kari

    2010-01-01

    Document available in extended abstract form only. In principle, in a KBS-3 type repository, the volume of a deposition hole is fixed and the bentonite buffer mass accordingly balanced to lead to the development of a suitable swelling pressure upon saturation. However, fractures intersecting the deposition holes give rise to the possibility that volume constrained conditions do not universally exist. Such fractures may provide pathways for the continued, localised, free swelling of bentonite buffer material. Loss of mass from the deposition hole by extrusion into intersecting fractures may compromise the long-term safety and performance of the buffer component of the engineered barrier system. Furthermore, the continued hydration and expansion of extruded bentonite in these fracture environments could lead to the separation of colloid-sized (or larger) particles by diffusion or shear which may have to be accounted for in possible radionuclide migration scenarios. Geochemical conditions, with respect to both solution and material composition, are considered to play important roles regarding the fracture extrusion/erosion of bentonite buffer material. For example, calcium-montmorillonite exhibits limited free swelling relative to sodium-montmorillonite and the colloidal and rheological properties of montmorillonite dispersions are sensitive to the presence of electrolytes. Insofar as both the buffer material composition (due to ion exchange) and groundwater composition (dilution resulting from infiltration of glacial melt water) are expected to evolve with time, so too might the potential for fracture extrusion/erosion of buffer material vary over time. The hydraulic characteristics of the intersecting fracture are expected to influence the extrusion/erosion process as well. To evaluate the effect of material and solution composition on the potential for extrusion of buffer mass into intersecting fractures, a series of batch experiments were performed. In these

  13. Material testing of copper by extrusion-cutting

    DEFF Research Database (Denmark)

    Segalina, F.; De Chiffre, Leonardo

    2017-01-01

    was developed and implemented on a CNC lathe. An investigation was carried out extrusion-cutting copper discs using high-speed-steel cutting tools at 100 m/min cutting speed. Flow stress values for copper under machining-relevant conditions were obtained from measurement of the extrusion-cutting force...

  14. Melting under shock compression

    International Nuclear Information System (INIS)

    Bennett, B.I.

    1980-10-01

    A simple model, using experimentally measured shock and particle velocities, is applied to the Lindemann melting formula to predict the density, temperature, and pressure at which a material will melt when shocked from room temperature and zero pressure initial conditions

  15. Disentanglement Effects on the Welding Behaviour of Polymer Melts during the Fused-Filament-Fabrication Method for Additive Manufacturing

    OpenAIRE

    McIlroy, Claire; Olmsted, Peter

    2017-01-01

    Although 3D printing has the potential to transform manufacturing processes, the strength of printed parts often does not rival that of traditionally-manufactured parts. The fused-filament fabrication method involves melting a thermoplastic, followed by layer-by-layer extrusion of the molten viscoelastic material to fabricate a three-dimensional object. The strength of the welds between layers is controlled by interdiffusion and entanglement of the melt across the interface. However, diffusio...

  16. Seismic Evidence for Possible Slab Melting from Strong Scattering Waves

    Directory of Open Access Journals (Sweden)

    Cheng-Horng Lin

    2011-01-01

    Full Text Available Slab melting in young and hot subduction zones has been studied using geochemical observations and thermal modelling, but there are few data from seismic studies to confirm slab melting. Also the detailed geometry in the deep part of the melting slab is often ambiguous in that the intraslab earthquakes within the Wadati-Benioff zone are only limited to shallower depths. To improve our understanding of both the seismic features and geometry found in a young and hot subducted slab, I analyzed anomalous moonquake-like seismograms that were generated by an intermediate-depth earthquake recorded in central Japan. For this study, possible reflected (or scattered sources were examined using detailed analyses of particle motions and a grid search for travel-time differences between the direct and later P-waves. The results show that using strong seismic scattering, slab melting is likely occurring in the deeper, flexing part of the subducted Philippine Sea plate. Because the subducted Philippine Sea plate in central Japan is young and therefore hot, partial melting might have taken place to produce abundant melting spots in the subducted slab. Melting spots, identified as ¡§bright spots,¡¨ could efficiently reflect or scatter seismic energy and generate many later phases with large amplitudes.

  17. Melting of Dense Sodium

    International Nuclear Information System (INIS)

    Gregoryanz, Eugene; Degtyareva, Olga; Hemley, Russell J.; Mao, Ho-kwang; Somayazulu, Maddury

    2005-01-01

    High-pressure high-temperature synchrotron diffraction measurements reveal a maximum on the melting curve of Na in the bcc phase at ∼31 GPa and 1000 K and a steep decrease in melting temperature in its fcc phase. The results extend the melting curve by an order of magnitude up to 130 GPa. Above 103 GPa, Na crystallizes in a sequence of phases with complex structures with unusually low melting temperatures, reaching 300 K at 118 GPa, and an increased melting temperature is observed with further increases in pressure

  18. Study of the microstructure evolution of ferritic stainless ODS steels during hot working

    International Nuclear Information System (INIS)

    Karch, Abdellatif

    2014-01-01

    The production of ODS steels involves a powder consolidation step usually using the hot extrusion (HE) process. The anisotropic properties of extruded materials, especially in the ODS ferritic grades (≥wt%12Cr), need a better understanding of the metallurgical phenomena which may occur during HE and lead to the observed microstructure. The hot working behavior of these materials is of particular interest. The methodology of this work includes the microstructure analysis after interrupted hot extrusion, hot torsion and hot compression (1000-1200 C) tests of ferritic steels with 14%Cr and different amounts in Ti and Y 2 O 3 . The microstructure evolution during hot extrusion process is associated with continuous dynamic recrystallization (CDRX). It leads to the creation of new grains by the formation of low angle boundaries, and then the increase of their misorientation under plastic deformation. The investigations highlight also the role of precipitation on the kinetics of this mechanism; it remains incomplete in the presence of fine and dense nano-precipitates. After hot deformation in torsion and compression, it is noticed that both precipitates and temperature deformation have a significant impact on the deformation mechanisms and microstructure evolution. Indeed, the CDRX is dominant when temperature and amount of reinforcement are limited. However, when they are increased, limited microstructure evolution is observed. In this case, the results are interpreted through a mechanism of strain accommodation at grain boundaries, with low dislocation activity in the bulk of the grains. (author) [fr

  19. Extrusion Pretreatment of Lignocellulosic Biomass: A Review

    Directory of Open Access Journals (Sweden)

    Jun Zheng

    2014-10-01

    Full Text Available Bioconversion of lignocellulosic biomass to bioethanol has shown environmental, economic and energetic advantages in comparison to bioethanol produced from sugar or starch. However, the pretreatment process for increasing the enzymatic accessibility and improving the digestibility of cellulose is hindered by many physical-chemical, structural and compositional factors, which make these materials difficult to be used as feedstocks for ethanol production. A wide range of pretreatment methods has been developed to alter or remove structural and compositional impediments to (enzymatic hydrolysis over the last few decades; however, only a few of them can be used at commercial scale due to economic feasibility. This paper will give an overview of extrusion pretreatment for bioethanol production with a special focus on twin-screw extruders. An economic assessment of this pretreatment is also discussed to determine its feasibility for future industrial cellulosic ethanol plant designs.

  20. Cause of Damage. Hot cracking; Schadensursache Heissrissigkeit

    Energy Technology Data Exchange (ETDEWEB)

    Wader, Therese [BENTELER Steel/Tube GmbH, Paderborn (Germany). Vorentwicklung Werkstoffe

    2016-10-15

    Under certain conditions, Nb-containing stainless steels are susceptible to hot cracking. Such conditions include low melting phases on the grain boundaries, a coarse-grained microstructure such as cast structures, microstructure orientations towards the main tensile direction and high processing temperatures. The case of damage was characterized using metallographic and microanalytical methods. In the laboratory, the critical temperature range for the formation of hot cracks could furthermore specifically be localized under mechanical stresses by means of a dilatometer aiming at clearly verifying the cause of the damage, namely ''hot cracks''.

  1. Optimal design of an extrusion process for a hinge bracket

    International Nuclear Information System (INIS)

    Na, Geum Ju; Jang, Myung Geun; Kim, Jong Bong

    2016-01-01

    This study considers process design in forming a hinge bracket. A thin hinge bracket is typically produced by bending a sheet panel or welding a hollow bar into a sheet panel. However, the hinge bracket made by bending or welding does not have sufficient durability in severe operating conditions because of the stress concentration in the bended region or the low corrosion resistance of the welded region. Therefore, this study uses forming to produce the hinge bracket part of a foldable container and to ensure durability in difficult operating conditions. An extrusion process for a T-shaped hinge bracket is studied using finite element analysis. Preliminary analysis shows that a very high forging load is required to form the bracket by forging. Therefore, extrusion is considered as a candidate process. Producing the part through the extrusion process enables many brackets to be made in a single extrusion and through successive cutting of the extruded part, thereby reducing the manufacturing cost. The design focuses on reducing the extrusion load and on ensuring shape accuracy. An initial billet is designed to reduce the extrusion load and to obtain a geometrically accurate part. The extruded part is bent frequently because of uneven material flow. Thus, extrusion die geometries are designed to obtain straight parts.

  2. Optimal design of an extrusion process for a hinge bracket

    Energy Technology Data Exchange (ETDEWEB)

    Na, Geum Ju; Jang, Myung Geun; Kim, Jong Bong [Seoul National University, Seoul (Korea, Republic of)

    2016-05-15

    This study considers process design in forming a hinge bracket. A thin hinge bracket is typically produced by bending a sheet panel or welding a hollow bar into a sheet panel. However, the hinge bracket made by bending or welding does not have sufficient durability in severe operating conditions because of the stress concentration in the bended region or the low corrosion resistance of the welded region. Therefore, this study uses forming to produce the hinge bracket part of a foldable container and to ensure durability in difficult operating conditions. An extrusion process for a T-shaped hinge bracket is studied using finite element analysis. Preliminary analysis shows that a very high forging load is required to form the bracket by forging. Therefore, extrusion is considered as a candidate process. Producing the part through the extrusion process enables many brackets to be made in a single extrusion and through successive cutting of the extruded part, thereby reducing the manufacturing cost. The design focuses on reducing the extrusion load and on ensuring shape accuracy. An initial billet is designed to reduce the extrusion load and to obtain a geometrically accurate part. The extruded part is bent frequently because of uneven material flow. Thus, extrusion die geometries are designed to obtain straight parts.

  3. Fabrication of three-dimensional scaffolds using precision extrusion deposition with an assisted cooling device.

    Science.gov (United States)

    Hamid, Q; Snyder, J; Wang, C; Timmer, M; Hammer, J; Guceri, S; Sun, W

    2011-09-01

    In the field of biofabrication, tissue engineering and regenerative medicine, there are many methodologies to fabricate a building block (scaffold) which is unique to the target tissue or organ that facilitates cell growth, attachment, proliferation and/or differentiation. Currently, there are many techniques that fabricate three-dimensional scaffolds; however, there are advantages, limitations and specific tissue focuses of each fabrication technique. The focus of this initiative is to utilize an existing technique and expand the library of biomaterials which can be utilized to fabricate three-dimensional scaffolds rather than focusing on a new fabrication technique. An expanded library of biomaterials will enable the precision extrusion deposition (PED) device to construct three-dimensional scaffolds with enhanced biological, chemical and mechanical cues that will benefit tissue generation. Computer-aided motion and extrusion drive the PED to precisely fabricate micro-scaled scaffolds with biologically inspired, porosity, interconnectivity and internal and external architectures. The high printing resolution, precision and controllability of the PED allow for closer mimicry of tissues and organs. The PED expands its library of biopolymers by introducing an assisting cooling (AC) device which increases the working extrusion temperature from 120 to 250 °C. This paper investigates the PED with the integrated AC's capabilities to fabricate three-dimensional scaffolds that support cell growth, attachment and proliferation. Studies carried out in this paper utilized a biopolymer whose melting point is established to be 200 °C. This polymer was selected to illustrate the newly developed device's ability to fabricate three-dimensional scaffolds from a new library of biopolymers. Three-dimensional scaffolds fabricated with the integrated AC device should illustrate structural integrity and ability to support cell attachment and proliferation.

  4. Fabrication of three-dimensional scaffolds using precision extrusion deposition with an assisted cooling device

    Energy Technology Data Exchange (ETDEWEB)

    Hamid, Q; Snyder, J; Wang, C; Guceri, S; Sun, W [Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA (United States); Timmer, M; Hammer, J, E-mail: sunwei@drexel.edu [Advanced Technologies and Regenerative Medicine, Somerville, NJ (United States)

    2011-09-15

    In the field of biofabrication, tissue engineering and regenerative medicine, there are many methodologies to fabricate a building block (scaffold) which is unique to the target tissue or organ that facilitates cell growth, attachment, proliferation and/or differentiation. Currently, there are many techniques that fabricate three-dimensional scaffolds; however, there are advantages, limitations and specific tissue focuses of each fabrication technique. The focus of this initiative is to utilize an existing technique and expand the library of biomaterials which can be utilized to fabricate three-dimensional scaffolds rather than focusing on a new fabrication technique. An expanded library of biomaterials will enable the precision extrusion deposition (PED) device to construct three-dimensional scaffolds with enhanced biological, chemical and mechanical cues that will benefit tissue generation. Computer-aided motion and extrusion drive the PED to precisely fabricate micro-scaled scaffolds with biologically inspired, porosity, interconnectivity and internal and external architectures. The high printing resolution, precision and controllability of the PED allow for closer mimicry of tissues and organs. The PED expands its library of biopolymers by introducing an assisting cooling (AC) device which increases the working extrusion temperature from 120 to 250 deg. C. This paper investigates the PED with the integrated AC's capabilities to fabricate three-dimensional scaffolds that support cell growth, attachment and proliferation. Studies carried out in this paper utilized a biopolymer whose melting point is established to be 200 deg. C. This polymer was selected to illustrate the newly developed device's ability to fabricate three-dimensional scaffolds from a new library of biopolymers. Three-dimensional scaffolds fabricated with the integrated AC device should illustrate structural integrity and ability to support cell attachment and proliferation.

  5. Fabrication of three-dimensional scaffolds using precision extrusion deposition with an assisted cooling device

    International Nuclear Information System (INIS)

    Hamid, Q; Snyder, J; Wang, C; Guceri, S; Sun, W; Timmer, M; Hammer, J

    2011-01-01

    In the field of biofabrication, tissue engineering and regenerative medicine, there are many methodologies to fabricate a building block (scaffold) which is unique to the target tissue or organ that facilitates cell growth, attachment, proliferation and/or differentiation. Currently, there are many techniques that fabricate three-dimensional scaffolds; however, there are advantages, limitations and specific tissue focuses of each fabrication technique. The focus of this initiative is to utilize an existing technique and expand the library of biomaterials which can be utilized to fabricate three-dimensional scaffolds rather than focusing on a new fabrication technique. An expanded library of biomaterials will enable the precision extrusion deposition (PED) device to construct three-dimensional scaffolds with enhanced biological, chemical and mechanical cues that will benefit tissue generation. Computer-aided motion and extrusion drive the PED to precisely fabricate micro-scaled scaffolds with biologically inspired, porosity, interconnectivity and internal and external architectures. The high printing resolution, precision and controllability of the PED allow for closer mimicry of tissues and organs. The PED expands its library of biopolymers by introducing an assisting cooling (AC) device which increases the working extrusion temperature from 120 to 250 deg. C. This paper investigates the PED with the integrated AC's capabilities to fabricate three-dimensional scaffolds that support cell growth, attachment and proliferation. Studies carried out in this paper utilized a biopolymer whose melting point is established to be 200 deg. C. This polymer was selected to illustrate the newly developed device's ability to fabricate three-dimensional scaffolds from a new library of biopolymers. Three-dimensional scaffolds fabricated with the integrated AC device should illustrate structural integrity and ability to support cell attachment and proliferation.

  6. Chain Extension and Thermal Behavior of Recycled Poly(Ethylene Terephthalate Modified by Reactive Extrusion with Triphenyl Phosphite

    Directory of Open Access Journals (Sweden)

    Qin Dan

    2016-01-01

    Full Text Available Reactive extrusion experiments of recycled PET fabrics (R-PET were carried out in a Haake torque rheometer with triphenyl phosphite (TPP and thermal behavior of modified R-PET was investigated by differential scanning calorimetry (DSC. The reaction mechanism which TPP acts as a cross-linker is verified by the experiment of phosphorus elemental analysis. DSC results show the presence of reaction residues may not modify melting temperature Tm and crystallization temperature Tc is controlled by the combined effect of molecular weight and reaction residues.

  7. Fabricating tungsten crucibles by drawing and extrusion spinning

    International Nuclear Information System (INIS)

    Edstrom, C.M.

    1981-01-01

    The fabrication of seamless tungsten crucibles 127-mm ID x 265-mm high x 6.25-mm wall thickness (5 in. x 10 1/2 in. x 1/4 in.) involved three drawing operations and extrusion spinning. The success of the drawing operations came from a combination of low draw reduction percentage, generous draw radii, large punch-to-die clearance, and attention to drawing temperature. The extrusion spinning success related to good drawn-cup-to-spinning-mandrel fit prior to making the extrusion passes, removal of stress risers in the part prior to spinning, and special attention to part and mandrel temperature

  8. Orthodontic extrusion in the transitional dentition: a simple technique.

    LENUS (Irish Health Repository)

    Darby, Laura J

    2009-11-01

    Extrusion of teeth may be necessary in cases of delayed eruption, primary retention, traumatically intruded teeth, or subgingivally fractured teeth. Removable appliances are advantageous, as anchorage is not as tooth-dependant as in the case of fixed appliances. They are cost-effective, operator friendly, and a valuable treatment option to consider in cases where extrusion of anterior teeth in the transitional dentition is necessary. The purpose of this paper was to describe a simple, cost-effective technique using a removable appliance for extrusion of incisors in the transitional dentition.

  9. FEM analysis of hollow hub forming in rolling extrusion process

    Directory of Open Access Journals (Sweden)

    J. Bartnicki

    2014-10-01

    Full Text Available In this paper are presented the results of numerical calculations of rolling extrusion process of a hollow hub. As the flanges manufacturing at both sides of the product is required, in the analyzed process of rolling extrusion, a rear bumper was implemented as additional tool limiting axial metal flow. Numerical calculations of the hub forming process were conducted basing on finite element method, applying software Deform3D and Simufact in conditions of three dimensional state of strain. The obtained satisfactory results show that it is possible to conduct the further research works of experimental character, with the application of a modernized aggregate for the rolling extrusion process PO-2.

  10. Extrusion: An environmentally friendly process for PEMFC membrane elaboration

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, J.-Y.; Iojoiu, C.; Marechal, M. [LEPMI, UMR 5631 CNRS-INPG-UJF, ENSEEG, BP 75, F-38402, Saint Martin d' Heres (France); Chabert, F.; El Kissi, N. [Rheologie, UMR 5520 CNRS-INPG-UJF, ENSHMG, BP 53, F-38041, Grenoble (France); Salomon, J.; Mercier, R. [LMOPS UMR CNRS 5041, BP 24, F-69390 Vernaison (France); Piffard, Y. [CNRS Universite de Nantes, Institut des Materiaux Jean Rouxel, UMR 6502, BP 32229, F-44322, Nantes Cedex 3 (France); Galiano, H. [CEA, Le Ripault Research Center, BP 16, F-37260, Monts (France)

    2007-12-31

    The paper deals with the use of extrusion to process PEMFC filled and unfilled membranes. Several routes including the sulfonation of filled and unfilled extruded membranes and the extrusion of filled and unfilled ionomers are reported. Thanks to the use of selected water-soluble aid process plasticizers, acid and alkaline forms of sulfonated polyethersulfone were, for the first time, successfully extruded. The extrusion process did not lead to any degradation of the ionomer performances. Decreasing the membrane cost while using environmentally friendly elaboration conditions, it should be helpful to an industrial production. In addition, avoiding filler sedimentation it should allow homogeneous composite membranes to be obtained. (author)

  11. HOT 2017

    DEFF Research Database (Denmark)

    Hannibal, Sara Stefansen

    HOT er en kvalitativ undersøgelse, der hvert år diskuterer og undersøger en lille udvalgt skare af danskkyndige fagpersoners bud på, hvad de er optagede af på literacyområdet her og nu – altså hvilke emner, de vil vurdere som aktuelle at forholde sig til i deres nuværende praksis.......HOT er en kvalitativ undersøgelse, der hvert år diskuterer og undersøger en lille udvalgt skare af danskkyndige fagpersoners bud på, hvad de er optagede af på literacyområdet her og nu – altså hvilke emner, de vil vurdere som aktuelle at forholde sig til i deres nuværende praksis....

  12. 75 FR 57441 - Aluminum Extrusions From the People's Republic of China: Alignment of Final Countervailing Duty...

    Science.gov (United States)

    2010-09-21

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-570-968] Aluminum Extrusions From the... countervailing duty investigation of aluminum extrusions from the People's Republic of China (PRC) with the final... antidumping duty investigations on aluminum extrusions from the PRC. See Aluminum Extrusions from the People's...

  13. 75 FR 69403 - Aluminum Extrusions From the People's Republic of China: Notice of Preliminary Determination of...

    Science.gov (United States)

    2010-11-12

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-967] Aluminum Extrusions From the... Commerce (``Department'') preliminarily determines that aluminum extrusions from the People's Republic of... of aluminum extrusions from the PRC filed in proper form by the Aluminum Extrusions Fair Trade...

  14. Preparation of High Modulus Poly(Ethylene Terephthalate: Influence of Molecular Weight, Extrusion, and Drawing Parameters

    Directory of Open Access Journals (Sweden)

    Jian Min Zhang

    2017-01-01

    Full Text Available Poly(ethylene terephthalate (PET which is one of the most commercially important polymers, has for many years been an interesting candidate for the production of high performance fibres and tapes. In current study, we focus on investigating the effects of the various processing variables on the mechanical properties of PET produced by a distinctive process of melt spinning and uniaxial two-stage solid-state drawing (SSD. These processing variables include screw rotation speed during extrusion, fibre take-up speed, molecular weight, draw-ratio, and drawing temperature. As-spun PET production using a single-screw extrusion process was first optimized to induce an optimal polymer microstructure for subsequent drawing processes. It was found that less crystallization which occurred during this process would lead to better drawability, higher draw-ratio, and mechanical properties in the subsequent SSD process. Then the effect of drawing temperature (DT in uniaxial two-stage SSD process was studied to understand how DT (

  15. Seismogenic frictional melting in the magmatic column as the driving force of stick-slip motion

    Science.gov (United States)

    Kendrick, J. E.; Lavallee, Y.; Hirose, T.; Di Toro, G.; Hornby, A.; De Angelis, S.; Henton De Angelis, S.; Ferk, A.; Hess, K.; Leonhardt, R.; Dingwell, D. B.

    2013-12-01

    Lava dome eruptions subjected to high extrusion rates commonly evolve from endogenous to exogenous growth and limits to their structural stability hold catastrophic potential as explosive eruption triggers. In the conduit strain localisation in magma, accompanied by seismogenic failure, marks the onset of brittle magma ascent dynamics. The rock record of exogenous dome structures preserves vestiges of cataclastic processes and of thermal anomalies, key to unravelling subsurface processes. A combined structural, thermal and magnetic investigation of shear bands from Mount St. Helens (MSH) and Soufrière Hills volcano (SHV) reveal evidence of faulting and frictional melting within the magmatic column. High velocity rotary shear (HVR) experiments demonstrate the propensity for melting of andesitic and dacitic material (from SHV and MSH respectively) at upper conduit stress conditions. Such melting events may be linked to the step-wise extrusion of magma accompanied by repetitive long-period (LP) seismicity. Using a source duration calculated from the waveforms at seismic stations around SHV, and slip distance per drumbeat calculated from extrusion rate, frictional melting of SHV andesite in a high velocity rotary shear apparatus can be achieved at small slip distances (HVR experiments which mimic rapid velocity fluctuations in stick-slip behavior demonstrate velocity-weakening behavior of melt, with a tendency for unstable slip. We postulate that pseudotachylyte generation could be the underlying cause of stick-slip motion and associated seismic 'drumbeats', which are so commonly observed at dome-building volcanoes, allowing for a fixed spatial locus and the occurrence of 'families' of similar seismic events. We conclude that, given the ease with which melting is achieved in volcanic rocks, and considering the high ambient temperatures in volcanic conduits, frictional melting is a highly probable consequence of viscous magma ascent.

  16. Hot particles

    International Nuclear Information System (INIS)

    Merwin, S.E.; Moeller, M.P.

    1989-01-01

    Nuclear Regulatory Commission (NRC) licensees are required to assess the dose to skin from a hot particle contamination event at a depth of skin of7mg/cm 2 over an area of 1 cm 2 and compare the value to the current dose limit for the skin. Although the resulting number is interesting from a comparative standpoint and can be used to predict local skin reactions, comparison of the number to existing limits based on uniform exposures is inappropriate. Most incidents that can be classified as overexposures based on this interpretation of dose actually have no effect on the health of the worker. As a result, resources are expended to reduce the likelihood that an overexposure event will occur when they could be directed toward eliminating the cause of the problem or enhancing existing programs such as contamination control. Furthermore, from a risk standpoint, this practice is not ALARA because some workers receive whole body doses in order to minimize the occurrence of hot particle skin contaminations. In this paper the authors suggest an alternative approach to controlling hot particle exposures

  17. Core melt retention and cooling concept of the ERP

    Energy Technology Data Exchange (ETDEWEB)

    Weisshaeupl, H [SIEMENS/KWU, Erlangen (Germany); Yvon, M [Nuclear Power International, Paris (France)

    1996-12-01

    For the French/German European Pressurized Water Reactor (EPR) mitigative measures to cope with the event of a severe accident with core melt down are considered already at the design stage. Following the course of a postulated severe accident with reactor pressure vessel melt through one of the most important features of a future design must be to stabilize and cool the melt within the containment by dedicated measures. This measures should - as far as possible - be passive. One very promising solution for core melt retention seems to be a large enough spreading of the melt on a high temperature resistant protection layer with water cooling from above. This is the favorite concept for the EPR. In dealing with the retention of a molten core outside of the RPV several ``steps`` from leaving the RPV to finally stabilize the melt have to gone through. These steps are: collection of the melt; transfer of the melt; distribution of the melt; confining; cooling and stabilization. The technical features for the EPR solution of a large spreading of the melt are: Dedicated spreading chamber outside the reactor pit (area about 150 m{sup 2}); high temperature resistant protection layers (e.g. Zirconia bricks) at the bottom and part of the lateral structures (thus avoiding melt concrete interaction); reactor pit and spreading compartment are connected via a discharge channel which has a slope to the spreading area and is closed by a steel plate, which will resist the core melt for a certain time in order to allow a collection of the melt; the spreading compartments is connected with the In-Containment Refuelling Water Storage Tank (IRWST) with pipes for water flooding after spreading. These pipes are closed and will only be opened by the hot melt itself. It is shown how the course of the different steps mentioned above is processed and how each of these steps is automatically and passively achieved. (Abstract Truncated)

  18. Poly(lactic acid (PLA Based Tear Resistant and Biodegradable Flexible Films by Blown Film Extrusion

    Directory of Open Access Journals (Sweden)

    Norma Mallegni

    2018-01-01

    Full Text Available Poly(lactic acid (PLA was melt mixed in a laboratory extruder with poly(butylene adipate-co-terephthalate (PBAT and poly(butylene succinate (PBS in the presence of polypropylene glycol di glycidyl ether (EJ400 that acted as both plasticizer and compatibilizer. The process was then scaled up in a semi-industrial extruder preparing pellets having different content of a nucleating agent (LAK. All of the formulations could be processed by blowing extrusion and the obtained films showed mechanical properties dependent on the LAK content. In particular the tearing strength showed a maximum like trend in the investigated composition range. The films prepared with both kinds of blends showed a tensile strength in the range 12–24 MPa, an elongation at break in the range 150–260% and a significant crystallinity.

  19. Model of interfacial melting

    DEFF Research Database (Denmark)

    Mouritsen, Ole G.; Zuckermann, Martin J.

    1987-01-01

    A two-dimensional model is proposed to describe systems with phase transitions which take place in terms of crystalline as well as internal degrees of freedom. Computer simulation of the model shows that the interplay between the two sets of degrees of freedom permits observation of grain-boundar......-boundary formation and interfacial melting, a nonequilibrium process by which the system melts at the boundaries of a polycrystalline domain structure. Lipid membranes are candidates for systems with pronounced interfacial melting behavior....

  20. Pressure effects on viscosity and flow stability of polyethylene melts during extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, Enric Santanach; Kissi, Nadia El; Piau, Jean-Michel; Toussaint, Fabrice; Nigen, Sophie [Domaine Universitaire, Laboratoire de Rheologie, Universite Joseph Fourier-Grenoble I, Institut National Polytechnique de Grenoble, CNRS (UMR 5520), B. P. 53, Grenoble cedex 9 (France)

    2006-01-01

    In the present work, the effects of pressure on the viscosity and flow stability of four commercial grade polyethylenes (PEs) have been studied: linear-low-density polyethylene copolymer, high-density polyethylene, metallocene polyethylenes with short-chain branches (mPE-SCB), and metallocene polyethylenes with long chain branching (mPE-LCB). The range of shear rates considered covers both stable and unstable flow regimes. ''Enhanced exit-pressure'' experiments have been performed attaining pressures of the order of 500 x 10{sup 5} Pa at the die exit. The necessary experimental conditions have been clearly defined so that dissipative heating can be neglected and pressure effects isolated. The results obtained show an exponential increase in both shear and entrance-flow pressure drop with mean pressure when shear rate is fixed and as long as flow is stable. These pressure effects are described by two pressure coefficients, {beta}{sub S} under shear and, {beta}{sub E} under elongation, that are calculated using time-pressure superposition and that are independent of mean pressure and flow rate. For three out of four PE, pressure coefficient values can be considered equal under shear and under elongation. However, for the mPE-LCB, the pressure coefficient under elongation is found to be about 30% lower than under shear. Flow instabilities in the form of oscillating flows or of upstream instabilities appear at lower shear rates as mean pressure increases. Nevertheless, the critical shear stress at which they are triggered remains independent of mean pressure. Moreover, it is found that the {beta}{sub S} values obtained for stable flows do not differ much from the values obtained during upstream instability regimes, and differ really from pressure effects observed under oscillating flow and slip conditions. (orig.)

  1. The friction influence on stress in micro extrusion

    Directory of Open Access Journals (Sweden)

    J. Piwnik

    2010-01-01

    Full Text Available Manufacturing of metallic parts by forming methods is industrially widespread due to high production rate, high accuracy, dimension’s and shape’s repeatability and good surface quality. The application of metal extrusion methods for the production of micro parts is possible, but there are some technological problems caused by small dimensions. Size effect is appearing. One of size effect symptom in micro extrusion, is a significant influence of rough contact between workpiece and tool while processing. In the case of rough contact without friction, material flows in the vicinity of the die surface. In order to explain more accurately a friction distribution in this area, the plastic wave friction model is proposed. This paper analyses specifications of a metal extrusion in micro scale. Using the friction model, a substitute friction shear factor mz and its influence on extrusion loading curves is determined in relationship to size of asperities.

  2. Adaptive Control of Freeze-Form Extrusion Fabrication Processes (Preprint)

    National Research Council Canada - National Science Library

    Zhao, Xiyue; Landers, Robert G; Leu, Ming C

    2008-01-01

    Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing process that extrudes high solids loading aqueous ceramic pastes in a layer-by-layer fashion below the paste freezing temperature for component fabrication...

  3. FORMING TUBES AND RODS OF URANIUM METAL BY EXTRUSION

    Science.gov (United States)

    Creutz, E.C.

    1959-01-27

    A method and apparatus are presented for the extrusion of uranium metal. Since uranium is very brittle if worked in the beta phase, it is desirable to extrude it in the gamma phase. However, in the gamma temperature range thc uranium will alloy with the metal of the extrusion dic, and is readily oxidized to a great degree. According to this patent, uranium extrusion in thc ganmma phase may be safely carried out by preheating a billet of uranium in an inert atmosphere to a trmperature between 780 C and 1100 C. The heated billet is then placed in an extrusion apparatus having dies which have been maintained at an elevated temperature for a sufficient length of time to produce an oxide film, and placing a copper disc between the uranium billet and the die.

  4. Chemical decontamination and melt densification

    International Nuclear Information System (INIS)

    Dillon, R.L.; Griggs, B.; Kemper, R.S.; Nelson, R.G.

    1976-01-01

    Preliminary studies on the chemical decontamination and densification of Zircaloy, stainless steel, and Inconel undissolved residues remaining after dissolution of the UO 2 --PuO 2 spent fuel material from sheared fuel bundles are reported. The studies were made on cold or very small samples to demonstrate the feasibility of the processes developed before proceeding to hot cell demonstrations with kg level of the sources. A promising aqueous decontamination method for Zr alloy cladding was developed in which oxidized surfaces are conditioned with HF prior to leaching with ammonium oxalate, ammonium citrate, ammonium fluoride, and hydrogen peroxide. Feasibility of molten salt decontamination of oxidized Zircaloy was demonstrated. A low melting alloy of Zircaloy, stainless steel, and Inconel was obtained in induction heated graphite crucibles. Segregated Zircaloy cladding sections were directly melted by the inductoslag process to yield a metal ingot suitable for storage. Both Zircaloy and Zircaloy--stainless steel--Inconel alloys proved to be highly satisfactory getters and sinks for recovered tritium

  5. Extrusion and properties of lead zirconate titanate piezoelectric ceramics

    DEFF Research Database (Denmark)

    Cai, S.; Millar, C.E.; Pedersen, L.

    1997-01-01

    The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates was investi......The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates...

  6. Instant blend from cassava derivatives produced by extrusion

    OpenAIRE

    Trombini, Fernanda Rossi Moretti; Mischan, Martha Maria; Leonel, Magali

    2016-01-01

    ABSTRACT: The current research aimed to evaluate the effects of extrusion parameters on the physical characteristics of extruded blends of cassava leaf flour and starch. A factorial central composite design with four independent variables and the response surface methodology were used to evaluate the results of color parameters (L*, a*, b*), water absorption index, water solubility index and paste properties, according to the variations in the leaf flour percentage (1.5 to 7.5%), extrusion te...

  7. A novel plastification agent for cemented carbides extrusion molding

    International Nuclear Information System (INIS)

    Ji-Cheng Zhou; Bai-Yun Huang

    2001-01-01

    A type of novel plastification agent for plasticizing powder extrusion molding of cemented carbides has been developed. By optimizing their formulation and fabrication method, the novel plastification agent, with excellent properties and uniform distribution characters, were manufactured. The thermal debinding mechanism has been studied, the extruding rheological characteristics and debinding behaviors have been investigated. Using the newly developed plastification agent, the cemented carbides extrusion rods, with diameter up to 25 mm, have been manufactured. (author)

  8. Experimental and numerical investigation of ram extrusion of bread dough

    Science.gov (United States)

    Mohammed, M. A. P.; Wanigasooriya, L.; Charalambides, M. N.

    2016-10-01

    An experimental and numerical study on ram extrusion of bread dough was conducted. A laboratory ram extrusion rig was designed and manufactured, where dies with different angles and exit radii were employed. Rate dependent behaviour was observed from tests conducted at different extrusion speeds, and higher extrusion pressure was reported for dies with decreasing exit radius. A finite element simulation of extrusion was performed using the adaptive meshing technique in Abaqus. Simulations using a frictionless contact between the billet and die wall showed that the model underestimates the response at high entry angles. On the other hand, when the coefficient of friction value was set to 0.09 as measured from friction experiments, the dough response was overestimated, i.e. the model extrusion pressure was much higher than the experimentally measured values. When a critical shear stress limit, τmax, was used, the accuracy of the model predictions improved. The results showed that higher die angles require higher τmax values for the model and the experiments to agree.

  9. Efeito do tipo de elemento de rosca na degradação de polipropileno durante múltiplas extrusões Effect of screw element on the polypropylene degradation during multiple extrusions

    Directory of Open Access Journals (Sweden)

    Ana Clélia Babetto

    2000-06-01

    Full Text Available A configuração da rosca de uma extrusora de dupla rosca modular pode ser projetada com vários tipos de elementos de condução e mistura, produzindo diferentes níveis de degradação no polímero fundido. Neste trabalho determinou-se o nível de degradação do polipropileno durante múltiplas extrusões em várias configurações de rosca, através de cromatografia por exclusão de tamanho e espectroscopia de infravermelho. Houve decréscimo do peso molecular e estreitamento da sua distribuição em função do número de extrusões e do aumento da agressividade da rosca, assim como, aumento da concentração de carbonilas e insaturações na cadeia polimérica. O elemento de mistura EM90 causou o maior nível de degradação e a adição de elementos de condução esquerdos ECE reduziram o nível de degradação.The screw configuration of a double screw extruder can be designed to contain kneading and conveying elements inducing different levels of degradation in the polymer melt. In this work the level of degradation in polypropylene have been measured after multiple extrusions for various screw configurations using Size Exclusion Chromatography and Infra-Red Spectroscopy. The average molecular weight and the polydispersity are reduced and the carbonyl and unsaturation indices increase as the number of extrusions and the agressiveness of the screw increase. The kneading element with 90 degrees caused the greater level of degradation and the addition of left hand elements have reduced the level of degradation.

  10. Melting the vacuum

    International Nuclear Information System (INIS)

    Rafelski, J.

    1998-01-01

    Results presented at the Quark Matter 97 conference, held in December in Tsukuba, Japan, have provided new insights into the confinement of quarks in matter. The current physics paradigm is that the inertial masses of protons and neutrons, and hence of practically all of the matter around us, originate in the zero-point energy caused by the confinement of quarks inside the small volume of the nucleon. Today, 25 years after Harald Fritzsch, Heinrich Leutwyler and Murray Gell-Mann proposed quantum chromodynamics (QCD) as a means for understanding strongly interacting particles such as nucleons and mesons, our understanding of strong interactions and quark confinement remains incomplete. Quarks and the gluons that bind them together have a ''colour'' charge that may be red, green or blue. But quarks are seen in particles that are white: baryons such as protons and neutrons consist of three quarks with different colour charges, while mesons consist of a quark and an antiquark, and again the colour charge cancels out. To prove that confinement arises from quark-gluon fluctuations in the vacuum that quantum theories dictate exists today, we need to find a way of freeing the colour charge of quarks. Experiments must therefore ''melt'' the vacuum to deconfine quarks and the colour charge. By colliding nuclei at high energies, we hope to produce regions of space filled with free quarks and gluons. This deconfined phase is known as the quark-gluon plasma. At the Tsukuba meeting, Scott Pratt of Michigan State University in the US discussed measurements that show that the hot dense state of matter created in these collisions exists for only 2x10 -23 s. So does the quark gluon plasma exist? No-one doubts that it did at one time, before the vacuum froze into its current state about 20 into the life of the universe, causing the nucleons to form as we know them today. The issue is whether we can recreate this early stage of the universe in laboratory experiments. And if we did

  11. Study of mechanical properties on powdermetalurgy aluminium matrix composites fabricated by stamping or extrusion

    International Nuclear Information System (INIS)

    Busquets, D.; Gomez, L.; Amigo, V.; Salvador-Moya, M. D.

    2005-01-01

    We have developed composite materials from AA6061 aluminium alloy powders used as matrix and ceramics powders of boron carbide, silicon carbide and boron nitride, used as reinforcements in 2.5, 5.0, 7.5 and 10% vol. by mechanical mixing and milling in planetary mill at 360 rpm vial velocity for 4 h followed of hot stamping and extrusion process on green compacts. Mechanical properties obtained from tensile tests are influenced by the heat treatment, reinforcement fractions and nature. Moreover, these mechanical characteristic are dependent from the processing route. Optical and Scanning Electron Microscopy analysis revealed the microstructure of materials and let describe the tripartite relation; structure-processing-properties, of the developed materials. (Author) 20 refs

  12. Melt inclusions: Chapter 6

    Science.gov (United States)

    ,; Lowenstern, J. B.

    2014-01-01

    Melt inclusions are small droplets of silicate melt that are trapped in minerals during their growth in a magma. Once formed, they commonly retain much of their initial composition (with some exceptions) unless they are re-opened at some later stage. Melt inclusions thus offer several key advantages over whole rock samples: (i) they record pristine concentrations of volatiles and metals that are usually lost during magma solidification and degassing, (ii) they are snapshots in time whereas whole rocks are the time-integrated end products, thus allowing a more detailed, time-resolved view into magmatic processes (iii) they are largely unaffected by subsolidus alteration. Due to these characteristics, melt inclusions are an ideal tool to study the evolution of mineralized magma systems. This chapter first discusses general aspects of melt inclusions formation and methods for their investigation, before reviewing studies performed on mineralized magma systems.

  13. Microstructures and recrystallization behavior of severely hot-deformed tungsten

    International Nuclear Information System (INIS)

    Mathaudhu, S.N.; De Rosset, A.J.; Hartwig, K.T.; Kecskes, L.J.

    2009-01-01

    When coarse-grained (CG) tungsten (W) is heavily worked by equal-channel angular extrusion (ECAE), the grain size is reduced to the ultrafine-grained/nanocrystalline regimes (UFG/NC) and the strength and ductility increase. Because of the brittle nature of CG W, the material must be hot-extruded, and, if the temperatures are near the recrystallization temperature (T rc ), gains in properties may not be maximized. In this study, the recrystallization behavior of ECAE-processed CG W is examined as a function of the imparted strain (i.e., number of extrusions) and the hot-working extrusion temperature. Up to four ECAE passes were performed in tooling with a 90 deg. channel intersection, and at temperatures of 1000 deg. C or 1200 deg. C. Subsequent 60 min annealing of the worked material to 1600 deg. C allowed for the determination of T rc . Vickers microhardness measurements and scanning electron microscopy, were used to characterize the microstructures in the as-worked and recrystallized states. The ECAE-processed W shows increased microstructural break-up and refinement with increasing strain and decreasing hot-working temperature in the fully worked state. T rc was determined to be ∼1400 deg. C, which is nearly independent of the number of extrusions and the working temperature. These results show that if ECAE is accomplished below 1400 deg. C (i.e., at 1000 deg. C or lower) the attractive properties of the UFG/NC-worked W may be retained. Specifically, below 1000 deg. C, with increasing strain imparted to the material, high hardness values with a concomitant grain size refinement (∼350 nm) could be expected

  14. Microstructure development and texture evolution of aluminum multi-port extrusion tube during the porthole die extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Fan, X.H. [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240 (China); School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Tang, D., E-mail: tangding@sjtu.edu.cn [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240 (China); School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Fang, W.L.; Li, D.Y.; Peng, Y.H. [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240 (China); School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2016-08-15

    Aluminum multi-port extrusion tube is processed by the porthole die extrusion and the internal tube walls are welded through the solid state metallurgical bonding. In order to observe the development of grains and their orientations under severe plastic deformation and solid state welding, the extrusion butt together with the die is quenched immediately after extrusion to preserve the grain structure in the processing. The forming histories of selected material points are obtained by analyzing the optical microscopy graph. The evolution of the microstructure along the forming path is characterized by electro backscattered diffraction. It is found that geometrical dynamic recrystallization happens in the process. Grains are elongated, scattered at the transition zone and shear intensive zone, and then pinched off when they are pushed out from the die orifice. The shear-type orientations are predominant at the surface layer on the longitudinal section of the tube web and have penetrated into the intermediate layer. The rolling-type orientations are formed at the central layer. Texture gradient through the thickness of the tube web is observed. And cube orientated grains are found at the seam weld region. - Highlights: •Microstructure of extrusion butt is preserved after the micro scale porthole die extrusion. •Grain morphology history along forming path is investigated. •Texture evolutions on three material flows are present. •Texture gradient exists on the longitudinal section of the internal wall of profile. •Rolling-type and cube textures are found at the solid state welding region.

  15. Net-shape and crack-free production of Nd–Fe–B magnets by hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Dirba, I., E-mail: dirba@fm.tu-darmstadt.de [Technische Universität Darmstadt, Materialwissenschaft, Alarich-Weiß-Str. 16, 64287 Darmstadt (Germany); IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden (Germany); Sawatzki, S. [Technische Universität Darmstadt, Materialwissenschaft, Alarich-Weiß-Str. 16, 64287 Darmstadt (Germany); IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden (Germany); Gutfleisch, O. [Technische Universität Darmstadt, Materialwissenschaft, Alarich-Weiß-Str. 16, 64287 Darmstadt (Germany)

    2014-03-15

    In order to reduce the amount of material waste and therefore to use the precious rare earth element Nd in a more efficient way, routes for the production of crack-free hot-deformed nanocrystalline Nd–Fe–B magnets (using melt-spun ribbons as a precursor) have been investigated. In contrast to the conventional route in which material flows into a cavity, pressing tool has been used in order to exert a back pressure during backward extrusion, leading to crack-free and net-shape production of radially oriented ring magnets, without detrimental influence on magnetic properties. Micrographs demonstrate overall good alignment of elongated platelet shaped grains with radially oriented c-axis in most parts of the ring. A mean remanence J{sub r} = 1.27 T and coercivity μ{sub 0i}H{sub c} = 1.5 T has been obtained. Degree of texture reaches around 0.7. Furthermore, die-upsetting has been performed for different degrees of deformation to obtain crack-free, mechanically and magnetically homogenous, axially oriented tablet magnets.

  16. Fuel Rod Melt Progression Simulation Using Low-Temperature Melting Metal Alloy

    International Nuclear Information System (INIS)

    Seung Dong Lee; Suh, Kune Y.; GoonCherl Park; Un Chul Lee

    2002-01-01

    downwards a blockage may be formed and grow both radially and axially. The velocity of the melt can be calculated from a force balance between the gravity and frictional losses at the melt-rod interface. When the heater rod is uncovered completely, the melt progression is initiated at the mid-point, which is the hot spot in the rod. However, the melting location is elevated as the water level rises because of the downward heat transfer. Considering the melt flow as a film, the steady-state film thickness on the cylindrical heater rod and the average velocity are computed. The steady-state film flow rate is determined in terms of the density, film thickness, and film velocity. (authors)

  17. A DNA Melting Exercise for a Large Laboratory Class

    Science.gov (United States)

    Levine, Lauren A.; Junker, Matthew; Stark, Myranda; Greenleaf, Dustin

    2015-01-01

    A simple and economical experimental setup is described that enables multiple individuals or groups within a laboratory class to measure the thermal melting of double stranded DNA simultaneously. The setup utilizes a basic spectrophotometer capable of measuring absorbance at 260 nm, UV plastic cuvettes, and a stirring hot plate. Students measure…

  18. Magma extrusion during the Ubinas 2013-2014 eruptive crisis based on satellite thermal imaging (MIROVA) and ground-based monitoring

    Science.gov (United States)

    Coppola, Diego; Macedo, Orlando; Ramos, Domingo; Finizola, Anthony; Delle Donne, Dario; del Carpio, José; White, Randall; McCausland, Wendy; Centeno, Riky; Rivera, Marco; Apaza, Fredy; Ccallata, Beto; Chilo, Wilmer; Cigolini, Corrado; Laiolo, Marco; Lazarte, Ivonne; Machaca, Roger; Masias, Pablo; Ortega, Mayra; Puma, Nino; Taipe, Edú

    2015-09-01

    After 3 years of mild gases emissions, the Ubinas volcano entered in a new eruptive phase on September 2nd, 2013. The MIROVA system (a space-based volcanic hot-spot detection system), allowed us to detect in near real time the thermal emissions associated with the eruption and provided early evidence of magma extrusion within the deep summit crater. By combining IR data with plume height, sulfur emissions, hot spring temperatures and seismic activity, we interpret the thermal output detected over Ubinas in terms of extrusion rates associated to the eruption. We suggest that the 2013-2014 eruptive crisis can be subdivided into three main phases: (i) shallow magma intrusion inside the edifice, (ii) extrusion and growing of a lava plug at the bottom of the summit crater coupled with increasing explosive activity and finally, (iii) disruption of the lava plug and gradual decline of the explosive activity. The occurrence of the 8.2 Mw Iquique (Chile) earthquake (365 km away from Ubinas) on April 1st, 2014, may have perturbed most of the analyzed parameters, suggesting a prompt interaction with the ongoing volcanic activity. In particular, the analysis of thermal and seismic datasets shows that the earthquake may have promoted the most intense thermal and explosive phase that culminated in a major explosion on April 19th, 2014. These results reveal the efficiency of space-based thermal observations in detecting the extrusion of hot magma within deep volcanic craters and in tracking its evolution. We emphasize that, in combination with other geophysical and geochemical datasets, MIROVA is an essential tool for monitoring remote volcanoes with rather difficult accessibility, like those of the Andes that reach remarkably high altitudes.

  19. Magma extrusion during the Ubinas 2013–2014 eruptive crisis based on satellite thermal imaging (MIROVA) and ground-based monitoring

    Science.gov (United States)

    Coppola, Diego; Macedo, Orlando; Ramos, Domingo; Finizola, Anthony; Delle Donne, Dario; del Carpio, Jose; White, Randall A.; McCausland, Wendy; Centeno, Riky; Rivera, Marco; Apaza, Fredy; Ccallata, Beto; Chilo, Wilmer; Cigolini, Corrado; Laiolo, Marco; Lazarte, Ivonne; Machaca, Roger; Masias, Pablo; Ortega, Mayra; Puma, Nino; Taipe, Edú

    2015-01-01

    After 3 years of mild gases emissions, the Ubinas volcano entered in a new eruptive phase on September 2nd, 2013. The MIROVA system (a space-based volcanic hot-spot detection system), allowed us to detect in near real time the thermal emissions associated with the eruption and provided early evidence of magma extrusion within the deep summit crater. By combining IR data with plume height, sulfur emissions, hot spring temperatures and seismic activity, we interpret the thermal output detected over Ubinas in terms of extrusion rates associated to the eruption. We suggest that the 2013–2014 eruptive crisis can be subdivided into three main phases: (i) shallow magma intrusion inside the edifice, (ii) extrusion and growing of a lava plug at the bottom of the summit crater coupled with increasing explosive activity and finally, (iii) disruption of the lava plug and gradual decline of the explosive activity. The occurrence of the 8.2 Mw Iquique (Chile) earthquake (365 km away from Ubinas) on April 1st, 2014, may have perturbed most of the analyzed parameters, suggesting a prompt interaction with the ongoing volcanic activity. In particular, the analysis of thermal and seismic datasets shows that the earthquake may have promoted the most intense thermal and explosive phase that culminated in a major explosion on April 19th, 2014.These results reveal the efficiency of space-based thermal observations in detecting the extrusion of hot magma within deep volcanic craters and in tracking its evolution. We emphasize that, in combination with other geophysical and geochemical datasets, MIROVA is an essential tool for monitoring remote volcanoes with rather difficult accessibility, like those of the Andes that reach remarkably high altitudes.

  20. Die Defects and Die Corrections in Metal Extrusion

    Directory of Open Access Journals (Sweden)

    Sayyad Zahid Qamar

    2018-05-01

    Full Text Available Extrusion is a very popular and multi-faceted manufacturing process. A large number of products for the automotive, aerospace, and construction sectors are produced through aluminum extrusion. Many defects in the extruded products occur because of the conditions of the dies and tooling. The problems in dies can be due to material issues, design and manufacturing, or severe usage. They can be avoided by maintaining the billet quality, by controlling the extrusion process parameters, and through routine maintenance. Die problems that occur on a day-to-day basis are mostly repairable and are rectified through various types of die correction operations. These defects and repair operations have not been reported in detail in the published literature. The current paper presents an in-depth description of repairable die defects and related die correction operations in metal extrusion. All major die defects are defined and classified, and their causes, preventive measures, and die correction operations are described. A brief frequency-based statistical study of die defects is also carried out to identify the most frequent die corrections. This work can be of direct benefit to plant engineers and operators and to researchers and academics in the field of metal extrusion.

  1. Simulation of steam explosion in stratified melt-coolant configuration

    International Nuclear Information System (INIS)

    Leskovar, Matjaž; Centrih, Vasilij; Uršič, Mitja

    2016-01-01

    Highlights: • Strong steam explosions may develop spontaneously in stratified configurations. • Considerable melt-coolant premixed layer formed in subcooled water with hot melts. • Analysis with MC3D code provided insight into stratified steam explosion phenomenon. • Up to 25% of poured melt was mixed with water and available for steam explosion. • Better instrumented experiments needed to determine dominant mixing process. - Abstract: A steam explosion is an energetic fuel coolant interaction process, which may occur during a severe reactor accident when the molten core comes into contact with the coolant water. In nuclear reactor safety analyses steam explosions are primarily considered in melt jet-coolant pool configurations where sufficiently deep coolant pool conditions provide complete jet breakup and efficient premixture formation. Stratified melt-coolant configurations, i.e. a molten melt layer below a coolant layer, were up to now believed as being unable to generate strong explosive interactions. Based on the hypothesis that there are no interfacial instabilities in a stratified configuration it was assumed that the amount of melt in the premixture is insufficient to produce strong explosions. However, the recently performed experiments in the PULiMS and SES (KTH, Sweden) facilities with oxidic corium simulants revealed that strong steam explosions may develop spontaneously also in stratified melt-coolant configurations, where with high temperature melts and subcooled water conditions a considerable melt-coolant premixed layer is formed. In the article, the performed study of steam explosions in a stratified melt-coolant configuration in PULiMS like conditions is presented. The goal of this analytical work is to supplement the experimental activities within the PULiMS research program by addressing the key questions, especially regarding the explosivity of the formed premixed layer and the mechanisms responsible for the melt-water mixing. To

  2. Melting point of yttria

    International Nuclear Information System (INIS)

    Skaggs, S.R.

    1977-06-01

    Fourteen samples of 99.999 percent Y 2 O 3 were melted near the focus of a 250-W CO 2 laser. The average value of the observed melting point along the solid-liquid interface was 2462 +- 19 0 C. Several of these same samples were then melted in ultrahigh-purity oxygen, nitrogen, helium, or argon and in water vapor. No change in the observed temperature was detected, with the exception of a 20 0 C increase in temperature from air to helium gas. Post test examination of the sample characteristics, clarity, sphericity, and density is presented, along with composition. It is suggested that yttria is superior to alumina as a secondary melting-point standard

  3. Effect of poly ethylene glycol on the mechanical and thermal properties of bioactive poly(ε-caprolactone) melt extrudates for pharmaceutical applications.

    Science.gov (United States)

    Douglas, P; Albadarin, Ahmad B; Sajjia, M; Mangwandi, Chirangano; Kuhs, Manuel; Collins, Maurice N; Walker, Gavin M

    2016-03-16

    This paper investigates the effects of polyethylene glycol (PEG), on the mechanical and thermal properties of nalidixic acid/poly ε-caprolactone (NA)/PCL blends prepared by hot melt extrusion. The blends were characterized by tensile and flexural analysis, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. Results show that loading PEG in the PCL had a detrimental effect on the tensile strength and toughness of the blends, reducing them by 20-40%. The partial miscibility of the PCL-PEG system, causes an increase in Tg. While increases in the crystallinity is attributed to the plasticisation effect of PEG and the nucleation effect of NA. The average crystal size increased by 8% upon PEG addition. Experimental data indicated that the addition of NA caused loss of the tensile strength and toughness of PCL. Thermal analysis of the PCL showed that on addition of the thermally unstable NA, thermal degradation occurred early and was autocatalytic. However, the NA did benefit from the heat shielding provided by the PCL matrix resulting in more thermally stable NA particles. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Force induced DNA melting

    International Nuclear Information System (INIS)

    Santosh, Mogurampelly; Maiti, Prabal K

    2009-01-01

    When pulled along the axis, double-strand DNA undergoes a large conformational change and elongates by roughly twice its initial contour length at a pulling force of about 70 pN. The transition to this highly overstretched form of DNA is very cooperative. Applying a force perpendicular to the DNA axis (unzipping), double-strand DNA can also be separated into two single-stranded DNA, this being a fundamental process in DNA replication. We study the DNA overstretching and unzipping transition using fully atomistic molecular dynamics (MD) simulations and argue that the conformational changes of double-strand DNA associated with either of the above mentioned processes can be viewed as force induced DNA melting. As the force at one end of the DNA is increased the DNA starts melting abruptly/smoothly above a critical force depending on the pulling direction. The critical force f m , at which DNA melts completely decreases as the temperature of the system is increased. The melting force in the case of unzipping is smaller compared to the melting force when the DNA is pulled along the helical axis. In the case of melting through unzipping, the double-strand separation has jumps which correspond to the different energy minima arising due to sequence of different base pairs. The fraction of Watson-Crick base pair hydrogen bond breaking as a function of force does not show smooth and continuous behavior and consists of plateaus followed by sharp jumps.

  5. Fragmentation of low-melting metals by collapsing steam bubbles

    International Nuclear Information System (INIS)

    Benz, R.

    1979-08-01

    When a hot melt meets a vaporable liquid of lower temperature, explosive vaporisation of the cooler liquid may be the result. This is called a steam explosion if a substantial amount of thermal energy is converted into mechanical energy. One important step in understanding about steam explosions is to explain the surface increase of the hot melt. There are several competing fragmentation hypotheses, but so far there has been no model to describe fragmentation criteria as well as the time curve of surface increase on the basis of physical processes. An overall model is now given for one of the possible fragmentation mechanisms, i.e. the division of the melt by collapsing steam bubbles. The model estimates the surface increase of the melt on the basis of heavy supercooled boiling, the heat transfer connected with it, the transfer of mechanical energy during steam bubble collapse, and the solidification of the melt. The results of the calculations have shown that basic experimental observations, e.g. time and extent of fragmentation, are well presented in the model with regard to their order of magnitude. The model presents a qualitatively correct description of the effects of important influencing factors, e.g. supercooling of the coolant or initial temperature of the melt. (orig.) [de

  6. Development of foams from linear polypropylene (PP) and high melt strength polypropylene (HMSPP) polymeric blends

    International Nuclear Information System (INIS)

    Cardoso, Elisabeth Carvalho Leite

    2009-01-01

    Foamed polymers are future materials, with a comprehensive application field. They can be used in order to improve appearance of insulation structures, for example, or to reduce costs involving materials. This work address to Isotactic Polypropylene / High Melt Strength Polypropylene blends, for foams production. Rheological behavior of polymer melt, especially referring to viscosity in processing temperature, plays a decisive role in applications where dominates extensional flow, as in case of foaming. If the viscosity is very low, it will correspond to a low melt strength, as in case of linear homopolymer (Isotact PP), and the foam will be prejudiced, due to the impossibility of expansion. Otherwise, if the viscosity is very high, with a high melt strength, the foam will collapse immediately after its formation. In order to get foams with an homogeneous and defined cellular structure, there were accomplished blends, 50% in weight, between linear homopolymer (isotactic PP) and HMSPP, from PP modified as per gamma radiation, in acetylene environment and at a 12.5 kGy doses. Extrusion process used a soluble foaming methodology, according to a processing/dissolution principle, which involves the dissolution of a Physical Blowing Agent (PBA), under 30 bar pressure, homogeneously mixed with polymeric melt. Extrusion conditions, that generally involve temperature, pressure and viscoelastic material flow control were experimentally investigated to define prevalent characteristics for producing foams. Nitrogen was the used PBA and process extrusion parameters were adapted to PP, HMSPP and their 50% in weight mixtures thereof. Major PP and HMSPP characteristics were obtained via melt Index and melt strength and thermal analyses (DSC/TGA), in order to make viable and to reproduce foaming as per extrusion process. Foams cellular morphology of PP, HMSPP and their 50% in weight mixtures thereof was investigated, with and without talc addition, as nucleating agent, by using

  7. Study on reactive extrusion processes of block copolymer

    International Nuclear Information System (INIS)

    Wu Lili; Jia Yuxi; Sun Sheng; Zhang Guofang; Zhao Guoqun; An Lijia

    2007-01-01

    The anionic copolymerization process of styrene-butadiene (S/B) block copolymer in a closely intermeshing co-rotating twin screw extruder with butyl-lithium initiator was studied. According to the anionic copolymerization mechanism and the reactive extrusion characteristics, the mathematical models of monomer conversion, average molecular weight and fluid viscosity during the anionic copolymerization of S/B were constructed, and then the reactive extrusion process was simulated by means of the finite volume method and the uncoupled semi-implicit iterative algorithm. Finally, the influence of the feeding mixture composition on conversion was discussed. The simulated results were nearly in agreement with the experimental results

  8. Study on lead extrusion damper as a seismic support

    International Nuclear Information System (INIS)

    Nomura, T.; Kojima, N.; Fujita, K.; Ito, T.

    1989-01-01

    The fundamental characteristics of two types of lead extrusion dampers (cylinder type, rotary type) for use as the nuclear power plant piping support of the elasto-plastic of damper are clarified. As a result, these lead extrusion dampers are found to have the following dynamic characteristics: hysteresis loop is both rectangular shape and bi-linear shape; maximum reaction force is independent of velocity and frequency but it increases as displacement exceeds the specified value; and the dissipated energy is very large and is independent of velocity, frequency and initial displacement (i.e., thermal expansion of pipings) in the range of test

  9. 75 FR 51243 - Aluminum Extrusions from the People's Republic of China: Postponement of Preliminary...

    Science.gov (United States)

    2010-08-19

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-967] Aluminum Extrusions from the... Department of Commerce (``the Department'') initiated an antidumping duty investigation on Aluminum... Aluminum Extrusions from the People's Republic of China: Initiation of Antidumping Duty Investigation, 75...

  10. Granular gel support-enabled extrusion of three-dimensional alginate and cellular structures.

    Science.gov (United States)

    Jin, Yifei; Compaan, Ashley; Bhattacharjee, Tapomoy; Huang, Yong

    2016-06-03

    Freeform fabrication of soft structures has been of great interest in recent years. In particular, it is viewed as a critical step toward the grand vision of organ printing--the on-demand design and fabrication of three-dimensional (3D) human organ constructs for implantation and regenerative medicine. The objective of this study is to develop a novel granular gel support material-enabled, two-step gelation-based 'printing-then-gelation' approach to fabricate 3D alginate structures using filament extrusion. Specifically, a granular Carbopol microgel bath holds the ungelled alginate structure being extruded, avoiding the instantaneous gelation of each printed layer as well as resultant surface tension-induced nozzle clogging. Since Carbopol microgels react with multivalent cations, which are needed for alginate crosslinking, gelatin is introduced as a sacrificial material to make an alginate and gelatin bioink for extrusion, which gels thermally (step-one gelation) to initially stabilize the printed structure for removal from Carbopol. Then gelatin is melted and diffused away while alginate is ionically crosslinked in a 37 °C calcium chloride bath (step-two gelation), resulting in an alginate structure. The proposed 'printing-then-gelation' approach works for alginate structure fabrication, and it is also applicable for the printing of cellular constructs and other similar homogeneous soft structures using a two-step or even multi-step approach. The main conclusions are: (1) 0.8% (w/v) Carbopol bath with a neutral pH value may be most suitable for soft structure printing; (2) it is most effective to use a 0.9% (w/v) NaCl solution to facilitate the removal of residual Carbopol; and (3) alginate structures fabricated using the proposed approach demonstrate better mechanical properties than those fabricated using the conventional 'gelation-while-printing' approach.

  11. Melting temperature of graphite

    International Nuclear Information System (INIS)

    Korobenko, V.N.; Savvatimskiy, A.I.

    2001-01-01

    Full Text: Pulse of electrical current is used for fast heating (∼ 1 μs) of metal and graphite specimens placed in dielectric solid media. Specimen consists of two strips (90 μm in thick) placed together with small gap so they form a black body model. Quasy-monocrystal graphite specimens were used for uniform heating of graphite. Temperature measurements were fulfilled with fast pyrometer and with composite 2-strip black body model up to melting temperature. There were fulfilled experiments with zirconium and tungsten of the same black body construction. Additional temperature measurements of liquid zirconium and liquid tungsten are made. Specific heat capacity (c P ) of liquid zirconium and of liquid tungsten has a common feature in c P diminishing just after melting. It reveals c P diminishing after melting in both cases over the narrow temperature range up to usual values known from steady state measurements. Over the next wide temperature range heat capacity for W (up to 5000 K) and Zr (up to 4100 K) show different dependencies of heat capacity on temperature in liquid state. The experiments confirmed a high quality of 2-strip black body model used for graphite temperature measurements. Melting temperature plateau of tungsten (3690 K) was used for pyrometer calibration area for graphite temperature measurement. As a result, a preliminary value of graphite melting temperature of 4800 K was obtained. (author)

  12. Melting behaviour of raw materials and recycled stone wool waste

    DEFF Research Database (Denmark)

    Schultz-Falk, Vickie; Agersted, Karsten; Jensen, Peter Arendt

    2018-01-01

    Stone wool is a widely used material for building insulation, to provide thermal comfort along with fire stability and acoustic comfort for all types of buildings. Stone wool waste generated either during production or during renovation or demolition of buildings can be recycled back into the sto...... wool melt production. This study investigates and compares the thermal response and melting behaviour of a conventional stone wool charge and stone wool waste. The study combines differential scanning calorimetry (DSC), hot stage microscopy (HSM) and X-ray diffraction (XRD). DSC reveals...... that the conventional charge and stone wool waste have fundamentally different thermal responses, where the charge experiences gas release, phase transition and melting of the individual raw materials. The stone wool waste experiences glass transition, crystallization and finally melting. Both DSC and HSM measurements...

  13. Final Technical Report - Advanced Optical Sensors to Minimize Energy Consumption in Polymer Extrusion Processes

    Energy Technology Data Exchange (ETDEWEB)

    Susan J. Foulk

    2012-07-24

    Project Objective: The objectives of this study are to develop an accurate and stable on-line sensor system to monitor color and composition on-line in polymer melts, to develop a scheme for using the output to control extruders to eliminate the energy, material and operational costs of off-specification product, and to combine or eliminate some extrusion processes. Background: Polymer extrusion processes are difficult to control because the quality achieved in the final product is complexly affected by the properties of the extruder screw, speed of extrusion, temperature, polymer composition, strength and dispersion properties of additives, and feeder system properties. Extruder systems are engineered to be highly reproducible so that when the correct settings to produce a particular product are found, that product can be reliably produced time after time. However market conditions often require changes in the final product, different products or grades may be processed in the same equipment, and feed materials vary from lot to lot. All of these changes require empirical adjustment of extruder settings to produce a product meeting specifications. Optical sensor systems that can continuously monitor the composition and color of the extruded polymer could detect process upsets, drift, blending oscillations, and changes in dispersion of additives. Development of an effective control algorithm using the output of the monitor would enable rapid corrections for changes in materials and operating conditions, thereby eliminating most of the scrap and recycle of current processing. This information could be used to identify extruder systems issues, diagnose problem sources, and suggest corrective actions in real-time to help keep extruder system settings within the optimum control region. Using these advanced optical sensor systems would give extruder operators real-time feedback from their process. They could reduce the amount of off-spec product produced and

  14. 76 FR 30650 - Aluminum Extrusions from the People's Republic of China: Antidumping Duty Order

    Science.gov (United States)

    2011-05-26

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-967] Aluminum Extrusions from the...''), the Department is issuing an antidumping duty order on aluminum extrusions from the People's Republic... of material injury by reason of imports of certain aluminum extrusions from the PRC, and its negative...

  15. 75 FR 73041 - Aluminum Extrusions From the People's Republic of China: Postponement of Final Determination of...

    Science.gov (United States)

    2010-11-29

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-967] Aluminum Extrusions From the... investigation of aluminum extrusions from the People's Republic of China (``PRC'') on April 27, 2010.\\1\\ On..., 2011. \\1\\ See Aluminum Extrusions from the People's Republic of China: Initiation of Antidumping Duty...

  16. 75 FR 34982 - Aluminum Extrusions from the People's Republic of China: Notice of Postponement of Preliminary...

    Science.gov (United States)

    2010-06-21

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-570-968] Aluminum Extrusions from the... in the Federal Register a notice of initiation of the countervailing duty investigation of aluminum extrusions from the People's Republic of China. See Aluminum Extrusions From the People's Republic of China...

  17. Melting of gold microclusters

    International Nuclear Information System (INIS)

    Garzon, I.L.; Jellinek, J.

    1991-01-01

    The transition from solid-like to liquid-like behavior in Au n , n=6, 7, 13, clusters is studied using molecular dynamics simulations. A Gupta-type potential with all-neighbour interactions is employed to incorporate n-body effects. The melting-like transition is described in terms of short-time averages of the kinetic energy per particle, root-mean-square bond length fluctuations and mean square displacements. A comparison between melting temperatures of Au n and Ni n clusters is presented. (orig.)

  18. Track with overlapping links for dry coal extrusion pumps

    Science.gov (United States)

    Saunders, Timothy; Brady, John D

    2014-01-21

    A chain for a particulate material extrusion pump includes a plurality of links, each of the plurality of links having a link body and a link ledge, wherein each link ledge of the plurality of links at least partially overlaps the link body of an adjacent one of the plurality of links.

  19. 75 FR 17436 - Certain Aluminum Extrusions From China

    Science.gov (United States)

    2010-04-06

    ... States at less than fair value and alleged to be subsidized by the Government of China. Unless the... response to a petition filed on March 31, 2010, by the Aluminum Extrusions Fair Trade Committee... presentation at the conference. A nonparty who has testimony that may aid the Commission's deliberations may...

  20. Main and interaction effects of extrusion temperature and usage ...

    African Journals Online (AJOL)

    The extruded full fat soybean (EFFSB) may be used in diet to satisfy the energy and protein requirements of fast growing broiler chickens. The main and interaction effects of three extrusion temperatures and two dietary levels of FFSB were studied on the performance, physiological enzymes and blood metabolites of broiler ...

  1. MM98.36 Strain Paths in Extrusion

    DEFF Research Database (Denmark)

    Lindegren, Maria; Wiwe, Birgitte; Wanheim, Tarras

    1998-01-01

    The extrusion process has been investigated for different geometries, in order to study the strain path of different material elements during their movements through the plastic zone. This is done by using the FEM code DEFORM and physical simulation with wax togehter with the coefficient method. ....... Calculations of strain paths have also been performed by ABAQUS....

  2. Load beam unit replaceable inserts for dry coal extrusion pumps

    Science.gov (United States)

    Saunders, Timothy; Brady, John D.

    2012-11-13

    A track assembly for a particulate material extrusion pump according to an exemplary aspect of the present disclosure includes a link assembly with a roller bearing. An insert mounted to a load beam located such that the roller bearing contacts the insert.

  3. Main and interaction effects of extrusion temperature and usage ...

    African Journals Online (AJOL)

    ali

    2012-10-30

    Oct 30, 2012 ... The main and interaction effects of three extrusion ... oil extraction and allow the use of a homegrown protein supplement in the .... Statistical analysis. The main and .... acceptable level of antitrypsin factor is 4 mg/g; this level.

  4. Effect of Thermo-extrusion Process Parameters on Selected Quality ...

    African Journals Online (AJOL)

    Effect of Thermo-extrusion Process Parameters on Selected Quality Attributes of Meat Analogue from Mucuna Bean Seed Flour. ... Nigerian Food Journal ... The product functional responses with coefficients of determination (R2) ranging between 0.658 and 0.894 were most affected by changes in barrel temperature and ...

  5. Growth of extrusions in localized cyclic plastic straining

    Czech Academy of Sciences Publication Activity Database

    Polák, Jaroslav; Sauzay, M.

    2009-01-01

    Roč. 500, č. 1-2 (2009), s. 122-129 ISSN 0921-5093 R&D Projects: GA ČR GA101/07/1500 Institutional research plan: CEZ:AV0Z20410507 Keywords : extrusion * strain localization * persistent slip band * vacancy Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.901, year: 2009

  6. Statistical reliability analyses of two wood plastic composite extrusion processes

    International Nuclear Information System (INIS)

    Crookston, Kevin A.; Mark Young, Timothy; Harper, David; Guess, Frank M.

    2011-01-01

    Estimates of the reliability of wood plastic composites (WPC) are explored for two industrial extrusion lines. The goal of the paper is to use parametric and non-parametric analyses to examine potential differences in the WPC metrics of reliability for the two extrusion lines that may be helpful for use by the practitioner. A parametric analysis of the extrusion lines reveals some similarities and disparities in the best models; however, a non-parametric analysis reveals unique and insightful differences between Kaplan-Meier survival curves for the modulus of elasticity (MOE) and modulus of rupture (MOR) of the WPC industrial data. The distinctive non-parametric comparisons indicate the source of the differences in strength between the 10.2% and 48.0% fractiles [3,183-3,517 MPa] for MOE and for MOR between the 2.0% and 95.1% fractiles [18.9-25.7 MPa]. Distribution fitting as related to selection of the proper statistical methods is discussed with relevance to estimating the reliability of WPC. The ability to detect statistical differences in the product reliability of WPC between extrusion processes may benefit WPC producers in improving product reliability and safety of this widely used house-decking product. The approach can be applied to many other safety and complex system lifetime comparisons.

  7. Effects of fermentation and extrusion on the proximate composition ...

    African Journals Online (AJOL)

    The effect of extrusion and fermentation on the proximate composition and organoleptic properties of six combinations (100:0, 90:10, 80:20, 70:30, 60:40 and 50:50) of sorghum - soya blend were investigated. A total number of 19 microorganisms were isolated during the fermentation of sorghum-soya extrudates; these ...

  8. Rheology and extrusion of low-grade paper and sludge

    Science.gov (United States)

    C. Tim Scott; Stefan Zauscher; Daniel J. Klingenberg

    1999-01-01

    This paper discusses efforts to characterize the rheological properties of pulps that include low-grade wastepapers and papermill sludges to determine their potential for extrusion and conversion into useful products. We investigated apparent changes in viscosity associated with the addition of typical inorganic paper fillers (calcium carbonate, kaolin clay, and...

  9. CFD-based optimization in plastics extrusion

    Science.gov (United States)

    Eusterholz, Sebastian; Elgeti, Stefanie

    2018-05-01

    This paper presents novel ideas in numerical design of mixing elements in single-screw extruders. The actual design process is reformulated as a shape optimization problem, given some functional, but possibly inefficient initial design. Thereby automatic optimization can be incorporated and the design process is advanced, beyond the simulation-supported, but still experience-based approach. This paper proposes concepts to extend a method which has been developed and validated for die design to the design of mixing-elements. For simplicity, it focuses on single-phase flows only. The developed method conducts forward-simulations to predict the quasi-steady melt behavior in the relevant part of the extruder. The result of each simulation is used in a black-box optimization procedure based on an efficient low-order parameterization of the geometry. To minimize user interaction, an objective function is formulated that quantifies the products' quality based on the forward simulation. This paper covers two aspects: (1) It reviews the set-up of the optimization framework as discussed in [1], and (2) it details the necessary extensions for the optimization of mixing elements in single-screw extruders. It concludes with a presentation of first advances in the unsteady flow simulation of a metering and mixing section with the SSMUM [2] using the Carreau material model.

  10. Cold Extrusion but Not Coating Affects Iron Bioavailability from Fortified Rice in Young Women and Is Associated with Modifications in Starch Microstructure and Mineral Retention during Cooking.

    Science.gov (United States)

    Hackl, Laura; Speich, Cornelia; Zeder, Christophe; Sánchez-Ferrer, Antoni; Adelmann, Horst; de Pee, Saskia; Tay, Fabian; Zimmermann, Michael B; Moretti, Diego

    2017-12-01

    Background: Rice can be fortified with the use of hot or cold extrusion or coating, but the nutritional qualities of the resulting rice grains have never been directly compared. Objective: Using fortified rice produced by coating or hot or cold extrusion, we compared 1 ) iron and zinc absorption with the use of stable isotopes, 2 ) iron and zinc retention during cooking, and 3 ) starch microstructure. Methods: We conducted 2 studies in young women: in study 1 [ n = 19; mean ± SD age: 26.2 ± 3.4 y; body mass index (BMI; in kg/m 2 ): 21.3 ± 1.6], we compared the fractional iron absorption (FAFe) from rice meals containing isotopically labeled ferric prophosphate ( 57 FePP), zinc oxide (ZnO), citric acid, and micronutrients fortified through hot extrusion (HER1) with rice meals fortified through cold extrusion containing 57 FePP, ZnO, citric acid, and micronutrients (CER); in study 2 ( n = 22; age: 24 ± 4 y; BMI: 21.2 ± 1.3), we compared FAFe and fractional zinc absorption (FAZn) from rice meals fortified through hot extrusion (HER2) compared with rice meals fortified through coating containing 57 FePP, ZnO, a citric acid and trisodium cirate mixture (CA/TSC), and micronutrients (COR) relative to rice meals extrinsically fortified with ferrous sulfate (reference). Rice types HER1 and CER contained citric acid, whereas types HER2 and COR contained CA/TSC. We assessed retention during standardized cooking experiments and characterized the rice starch microstructure. Results: FAFe (95% CI) was greater from CER [2.2% (1.4%, 3.4%)] than from HER1 [1.2% (0.7%, 2.0%)] ( P = 0.036). There was no difference in FAFe between HER2 [5.1% (3.7%, 7.1%)] and COR [4.0% (2.9%, 5.4%)] ( P = 0.14), but FAFe from COR was lower than that from the reference meal [6.6% (4.9%, 9.0%)] ( P = 0.003), and the geometric mean FAZn (95% CI) did not differ between HER2 [9.5% (7.9%, 11.6%)] and COR [9.6% (8.7%, 10.7%)] ( P = 0.92). Cooking in a rice-to-water ratio of 1:2 resulted in iron and zinc

  11. GLASS MELTING PHENOMENA, THEIR ORDERING AND MELTING SPACE UTILISATION

    Directory of Open Access Journals (Sweden)

    Němec L.

    2013-12-01

    Full Text Available Four aspects of effective glass melting have been defined – namely the fast kinetics of partial melting phenomena, a consideration of the melting phenomena ordering, high utilisation of the melting space, and effective utilisation of the supplied energy. The relations were defined for the specific melting performance and specific energy consumption of the glass melting process which involve the four mentioned aspects of the process and indicate the potentials of effective melting. The quantity “space utilisation” has been treated in more detail as an aspect not considered in practice till this time. The space utilisation was quantitatively defined and its values have been determined for the industrial melting facility by mathematical modelling. The definitions of the specific melting performance and specific energy consumption have been used for assessment of the potential impact of a controlled melt flow and high space utilisation on the melting process efficiency on the industrial scale. The results have shown that even the partial control of the melt flow, leading to the partial increase of the space utilisation, may considerably increase the melting performance, whereas a decrease of the specific energy consumption was determined to be between 10 - 15 %.

  12. Solar 'hot spots' are still hot

    Science.gov (United States)

    Bai, Taeil

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22.

  13. Solar hot spots are still hot

    International Nuclear Information System (INIS)

    Bai, T.

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22. 14 refs

  14. Crystal-rich lava dome extrusion during vesiculation: An experimental study

    Science.gov (United States)

    Pistone, Mattia; Whittington, Alan G.; Andrews, Benjamin J.; Cottrell, Elizabeth

    2017-11-01

    Lava dome-forming eruptions represent a common eruptive style and a major hazard at numerous active volcanoes worldwide. The extrusion mechanics of crystal-rich lava domes and the influence of volatiles on the transition from viscous to brittle behaviour during lava dome extrusion remain unclear. Understanding how gas exsolution and crystallinity control effusive versus explosive eruption behaviour is essential. Here, we present new experimental results on the rheology of synthesised, crystal-rich (50 to 80 vol% quartz crystals), hydrous (4.2 wt% H2O in the glass) dacite samples, which vesiculate from 5 to 27 vol% gas bubbles at high temperatures (from glass transition temperature to 797 °C) during deformation conducted in a parallel plate viscometer (constant stress at 0.63-0.64 MPa, and variable strain-rates ranging from 8.32·10- 8 to 3.58·10- 5 s- 1). The experiments reproduce certain aspects of lava dome deformation in volcanic conduits during vesiculation of the residual melt, instigated in the experiments by increasing temperature. During gas exsolution (i.e. nucleation and growth of gas-pressurised bubbles) and volume inflation, we find that the rheological lubrication of the system during deformation is strongly dictated by the initial crystallinity. At crystal contents < 60 vol%, gas bubbles form and coalesce during expansion and viscous deformation, favouring strain localisation and gas permeability within shear bands, which control the overall sample rheology. At crystallinities of 60 to 70 vol%, gas exsolution generates pressurisation (i.e. pore pressure increase) within the bubbles trapped in the solid crystal clusters, and embryonic formation of microscopic fractures through melt and crystals drives the system to a brittle behaviour. At higher crystallinity (80 vol%) vesiculation leads to large pressurisation, which then triggers extensive brittle fragmentation. Through macroscopic fractures, outgassing determines the rheological stalling of the

  15. Fabrication of SiCp/Al Alloy Composites by In-situ Vacuum Hot Press Process

    Energy Technology Data Exchange (ETDEWEB)

    Choi, S. W.; Hong, S. K.; Kim, Y. M.; Kang, C. S. [Chonnam National University, Kwangju (Korea); Chang, S. Y. [Hanyang University, Seoul (Korea)

    2001-07-01

    SiCp/pure Al and SiCp/2024Al MMCs were fabricated by in-situ VHP process designed specially just in this study which is composed of the vacuum hot press at range from R.T. to 500 deg.C and the continuous extrusion without canning process at 520 deg.C. It was investigated the effect of SiC particle size, volume fraction and extrusion ratio on the tensile properties and micro structure in all composites. In case of the 10:1 extrusion ratio, but SiCp/pure Al and SiCp/2024Al composites were shown a sound appearance and a good micro structure without crack of SiCp as well as uniform distribution of SiCp. However, in case of the 16:1 extrusion ratio, the number of cracked SiC particles more than increased in a higher volume fraction composite and 2024Al matrix composite compared with pure Al matrix one. The tensile strength of the composites reinforced smaller SiCp was higher than that of the bigger SiCp reinforced in same volume fraction and extrusion ratio. (author) 14 refs., 14 figs.

  16. Cell Extrusion: A Stress-Responsive Force for Good or Evil in Epithelial Homeostasis.

    Science.gov (United States)

    Ohsawa, Shizue; Vaughen, John; Igaki, Tatsushi

    2018-02-05

    Epithelial tissues robustly respond to internal and external stressors via dynamic cellular rearrangements. Cell extrusion acts as a key regulator of epithelial homeostasis by removing apoptotic cells, orchestrating morphogenesis, and mediating competitive cellular battles during tumorigenesis. Here, we delineate the diverse functions of cell extrusion during development and disease. We emphasize the expanding role for apoptotic cell extrusion in exerting morphogenetic forces, as well as the strong intersection of cell extrusion with cell competition, a homeostatic mechanism that eliminates aberrant or unfit cells. While cell competition and extrusion can exert potent, tumor-suppressive effects, dysregulation of either critical homeostatic program can fuel cancer progression. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. MELT-IIIB: an updated version of the melt code

    International Nuclear Information System (INIS)

    Tabb, K.K.; Lewis, C.H.; O'Dell, L.D.; Padilla, A. Jr.; Smith, D.E.; Wilburn, N.P.

    1979-04-01

    The MELT series is a reactor modeling code designed to investigate a wide variety of hypothetical accident conditions, particularly the transient overpower sequence. MELT-IIIB is the latest in the series

  18. Apical extrusion of debris: a literature review of an inherent occurrence during root canal treatment.

    Science.gov (United States)

    Tanalp, J; Güngör, T

    2014-03-01

    Extrusion of intracanal debris as well as irrigants is a common occurrence during root canal treatment, and no instrument or technique has thoroughly solved this problem. Because flare-ups may arise with any irritation directed towards periapical tissues, a shaping or irrigation technique should minimize the risk of apical extrusion, even though it may not be prevented. There has been a rapid evolution of root canal instruments and irrigation systems through the last decade, and many have been assessed for their debris extrusion potential. The purpose of this review was to identify publications regarding the evaluation of debris, bacteria and irrigant extrusion during root canal treatment. A PubMed, Ovid and MEDLINE search was conducted using the keywords "apical extrusion", "debris extrusion" and "endodontic treatment". The literature search extended over a period of more than 30 years up to 2012. Content of the review was limited to apical extrusion of debris and irrigants, extrusion of liquid by irrigation methods and bacterial extrusion. Issues relevant to apical extrusion were obtained by further search in the reference sections of the retrieved articles. The review provides an update on the current status of apical extrusion. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  19. Rock melting technology and geothermal drilling

    Science.gov (United States)

    Rowley, J. C.

    1974-01-01

    National awareness of the potential future shortages in energy resources has heightened interest in exploration and utilization of a variety of geothermal energy (GTE) reservoirs. The status of conventional drilling of GTE wells is reviewed briefly and problem areas which lead to higher drilling costs are identified and R and D directions toward solution are suggested. In the immediate future, an expanded program of drilling in GTE formations can benefit from improvements in drilling equipment and technology normally associated with oil or gas wells. Over a longer time period, the new rock-melting drill bits being developed as a part of the Los Alamos Scientific Laboratory's Subterrene Program offer new solutions to a number of problems which frequently hamper GTE drilling, including the most basic problem - high temperature. Two of the most favorable characteristics of rock-melting penetrators are their ability to operate effectively in hot rock and produce glass linings around the hole as an integral part of the drilling process. The technical advantages to be gained by use of rock-melting penetrators are discussed in relation to the basic needs for GTE wells.

  20. Effects of surface shape on the geometry and surface topography of the melt pool in low-power density laser melting

    KAUST Repository

    Kim, Youngdeuk

    2011-04-15

    The quantitative correlations between workpiece volume and melt pool geometry, as well as the flow and thermal features of the melt pool are established. Thermocapillary convections in melt pool with a deformable free surface are investigated with respect to surface shape and laser intensity. When the contact angle between the tangent to the top surface and the vertical wall at the hot center is acute, the free surface flattens, compared with that of the initial free surface. Otherwise, the free surface forms a bowl-like shape with a deep crater and a low peripheral rim when the contact angle at the hot center is obtuse. Increasing the workpiece volume at a fixed laser intensity and a negative radial height gradient cause linear decreases in the geometric size and magnitude of flow and temperature of the melt pool. Conversely, linear increases are observed with a positive radial height gradient. © 2011 American Institute of Chemical Engineers (AIChE).

  1. Numerical studies of the polymer melt flow in the extruder screw channel and the forming tool

    Science.gov (United States)

    Ershov, S. V.; Trufanova, N. M.

    2017-06-01

    To date, polymer compositions based on polyethylene or PVC is widely used as insulating materials. These materials processing conjugate with a number of problems during selection of the rational extrusion regimes. To minimize the time and cost when determining the technological regime uses mathematical modeling techniques. The paper discusses heat and mass transfer processes in the extruder screw channel, output adapter and the cable head. During the study were determined coefficients for three rheological models based on obtained viscosity vs. shear rate experimental data. Also a comparative analysis of this viscosimetric laws application possibility for studying polymer melt flow during its processing on the extrusion equipment was held. As a result of numerical study the temperature, viscosity and shear rate fields in the extruder screw channel and forming tool were obtained.

  2. Effect of Nano-clay on Rheological and Extrusion Foaming Process of a Block-Copolymerized Polypropylene

    Directory of Open Access Journals (Sweden)

    Wang Mingyi

    2016-01-01

    Full Text Available The effects of nano-clay and the corresponding coupling agent maleic anhydride grafted polypropylene (PP-g-MAH on thermal properties, rheological properties and extrusion foaming process of a block-copolymerized polypropylene (B-PP were studied. Supercritical CO2 (SC CO2 was used as the foaming agent with a concentration of 5wt%. Each step of foamed B-PP/ PP-g-MAH/ nano-clay composites processing is addressed, including mixing of the composites, manufacture of the composites, foaming process of the composites and characterization of the cell structure. The results showed that incorporation of nano-clay and PP-g-MAH caused reduced melt strength and complex viscosity of B-PP. However, the heterogeneous nucleation induced by nano-clay and PP-g-MAH improved the maximum foaming expansion ratio and cell-population density of B-PP foam.

  3. Melting of polydisperse hard disks

    NARCIS (Netherlands)

    Pronk, S.; Frenkel, D.

    2004-01-01

    The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find

  4. Thermodynamics of Oligonucleotide Duplex Melting

    Science.gov (United States)

    Schreiber-Gosche, Sherrie; Edwards, Robert A.

    2009-01-01

    Melting temperatures of oligonucleotides are useful for a number of molecular biology applications, such as the polymerase chain reaction (PCR). Although melting temperatures are often calculated with simplistic empirical equations, application of thermodynamics provides more accurate melting temperatures and an opportunity for students to apply…

  5. Pavement Snow Melting

    Energy Technology Data Exchange (ETDEWEB)

    Lund, John W.

    2005-01-01

    The design of pavement snow melting systems is presented based on criteria established by ASHRAE. The heating requirements depends on rate of snow fall, air temperature, relative humidity and wind velocity. Piping materials are either metal or plastic, however, due to corrosion problems, cross-linked polyethylene pipe is now generally used instead of iron. Geothermal energy is supplied to systems through the use of heat pipes, directly from circulating pipes, through a heat exchanger or by allowing water to flow directly over the pavement, by using solar thermal storage. Examples of systems in New Jersey, Wyoming, Virginia, Japan, Argentina, Switzerland and Oregon are presented. Key words: pavement snow melting, geothermal heating, heat pipes, solar storage, Wyoming, Virginia, Japan, Argentina, Klamath Falls.

  6. Transient fuel melting

    International Nuclear Information System (INIS)

    Roche, L.; Schmitz, F.

    1982-10-01

    The observation of micrographic documents from fuel after a CABRI test leads to postulate a specific mode of transient fuel melting during a rapid nuclear power excursion. When reaching the melt threshold, the bands which are characteristic for the solid state are broken statistically over a macroscopic region. The time of maintaining the fuel at the critical enthalpy level between solid and liquid is too short to lead to a phase separation. A significant life-time (approximately 1 second) of this intermediate ''unsolide'' state would have consequences on the variation of physical properties linked to the phase transition solid/liquid: viscosity, specific volume and (for the irradiated fuel) fission gas release [fr

  7. Influence of parameters controlling the extrusion step in fused filament fabrication (FFF) process applied to polymers using numerical simulation

    Science.gov (United States)

    Shahriar, Bakrani Balani; Arthur, Cantarel; France, Chabert; Valérie, Nassiet

    2018-05-01

    Extrusion is one of the oldest manufacturing processes; it is widely used for manufacturing finished and semi-finished products. Moreover, extrusion is also the main process in additive manufacturing technologies such as Fused Filament Fabrication (FFF). In FFF process, the parts are manufactured layer by layer using thermoplastic material. The latter in form of filament, is melted in the liquefier and then it is extruded and deposited on the previous layer. The mechanical properties of the printed parts rely on the coalescence of each extrudate with another one. The coalescence phenomenon is driven by the flow properties of the melted polymer when it comes out the nozzle just before the deposition step. This study aims to master the quality of the printed parts by controlling the effect of the parameters of the extruder on the flow properties in the FFF process. In the current study, numerical simulation of the polymer coming out of the extruder was carried out using Computational Fluid Dynamics (CFD) and two phase flow (TPF) simulation Level Set (LS) method by 2D axisymmetric module of COMSOL Multiphysics software. In order to pair the heat transfer with the flow simulation, an advection-diffusion equation was used. Advection-diffusion equation was implemented as a Partial Differential Equation (PDE) in the software. In order to define the variation of viscosity of the polymer with temperature, the rheological behaviors of two thermoplastics were measured by extensional rheometer and using a parallel-plate configuration of an oscillatory rheometer. The results highlight the influence of the environment temperature and the cooling rate on the temperature and viscosity of the extrudate exiting from the nozzle. Moreover, the temperature and its corresponding viscosity at different times have been determined using numerical simulation. At highest shear rates, the extrudate undergoes deformation from typical cylindrical shape. These results are required to predict the

  8. New Evidences on the Process Sensitivity of Some Renewable Blends Based on Starch considering Their Melt Rheological Properties

    Directory of Open Access Journals (Sweden)

    Doina Dimonie

    2016-01-01

    Full Text Available The degradability and processability of new renewable materials based on starch and PVOH were studied using the melt flow index (MFI method by measuring the melt rheological properties which depend not only on the extrusion conditions and material formulation but also on the macromolecule characteristics which can be modified by chemical degradation. These results were correlated with other material properties like color and cross-linking degree. The obtained results show that flowing in the melted state of the studied materials is accompanied by a second process of chains chemical degradation. It was observed that, at the same level of additivation, under identical extrusion conditions, the melted blends with corn starch as main component are highly mechanically sensitive and degrade mostly by chains scission and those with PVOH as major component are highly temperature sensitive and degrade mainly by cross-linking. The obtained results show also that each PVOH-starch blend requires particular formulation and individual windows of melt processing conditions. These results are a good proof that the MFI method is a good path to study the degradability and moldability of process sensitive polymeric materials like those based on starch and PVOH.

  9. Hot tub folliculitis

    Science.gov (United States)

    ... survives in hot tubs, especially tubs made of wood. Symptoms The first symptom of hot tub folliculitis ... may help prevent the problem. Images Hair follicle anatomy References D'Agata E. Pseudomonas aeruginosa and other ...

  10. Functionalization of whey proteins by reactive supercritical fluid extrusion

    Directory of Open Access Journals (Sweden)

    Khanitta Ruttarattanamongkol

    2012-09-01

    Full Text Available Whey protein, a by-product from cheese-making, is often used in a variety of food formulations due to its unsurpassednutritional quality and inherent functional properties. However, the possibilities for the improvement and upgrading of wheyprotein utilization still need to be explored. Reactive supercritical fluid extrusion (SCFX is a novel technique that has beenrecently reported to successfully functionalize commercially available whey proteins into a product with enhanced functionalproperties. The specific goal of this review is to provide fundamental understanding of the reinforcement mechanism andprocessing of protein functionalization by reactive SCFX process. The superimposed extrusion variables and their interactionmechanism affect the physico-chemical properties of whey proteins. By understanding the structure, functional properties andprocessing relationships of such materials, the rational design criteria for novel functionalized proteins could be developedand effectively utilized in food systems.

  11. Pellet manufacturing by extrusion-spheronization using process analytical technology

    DEFF Research Database (Denmark)

    Sandler, Niklas; Rantanen, Jukka; Heinämäki, Jyrki

    2005-01-01

    The aim of this study was to investigate the phase transitions occurring in nitrofurantoin and theophylline formulations during pelletization by extrusion-spheronization. An at-line process analytical technology (PAT) approach was used to increase the understanding of the solid-state behavior...... of the active pharmaceutical ingredients (APIs) during pelletization. Raman spectroscopy, near-infrared (NIR) spectroscopy, and X-ray powder diffraction (XRPD) were used in the characterization of polymorphic changes during the process. Samples were collected at the end of each processing stage (blending......, granulation, extrusion, spheronization, and drying). Batches were dried at 3 temperature levels (60 degrees C, 100 degrees C, and 135 degrees C). Water induced a hydrate formation in both model formulations during processing. NIR spectroscopy gave valuable real-time data about the state of water in the system...

  12. Numerical Studies of Low Cycle Fatigue in Forward Extrusion Dies

    DEFF Research Database (Denmark)

    Pedersen, Thomas Ø

    2000-01-01

    of describing the elastic-plastic material behaviour under cyclic loadings is used to study the effects of different pre-stressing concepts on the accumulation of plastic strain and the development of fatigue damage. The results show, that the accumulation of plastic strain in the critical region can......Forward extrusion dies typically fail due to transverse fatigue cracks or wear. Fatigue cracks are initiated in regions where the material is subjected to repeated plastic deformations, e.g. the transition radius in a forward extrusion die, in the present work, a material model capable...... be controlled by means of the pre-stressing system or the geometry of the die insert. (C) 2000 Elsevier Science B.V. All rights reserved....

  13. The effect of grain size on dynamic tensile extrusion behaviour

    Directory of Open Access Journals (Sweden)

    Park Leeju

    2015-01-01

    Full Text Available Dynamic tensile extrusion (DTE tests were conducted on coarse grained and ultrafine grained (UFG OFHC Cu, Interstitial free (IF Steel, and pure Ta. Equal channel angular pressing (ECAP of 16passes with Bc for Cu, IF Steel and 4 passes for Ta was employed to fabricated UFG materials. DTE tests were carried out by launching the sphere samples (Dia. 7.62 mm to the conical extrusion die at a speed of ∼500 m/sec. The fragmentation behavior of the soft-recovered fragments were examined and compared with each other. The DTE fragmentation behavior of CG and UFG was numerically simulated by the LS-DYNA FEM code.

  14. Equal channel angular extrusion of ultra-high molecular weight polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Reinitz, Steven D., E-mail: Steven.D.Reinitz.TH@Dartmouth.edu; Engler, Alexander J.; Carlson, Evan M.; Van Citters, Douglas W.

    2016-10-01

    Ultra-high molecular weight polyethylene (UHMWPE), a common bearing surface in total joint arthroplasty, is subject to material property tradeoffs associated with conventional processing techniques. For orthopaedic applications, radiation-induced cross-linking is used to enhance the wear resistance of the material, but cross-linking also restricts relative chain movement in the amorphous regions and hence decreases toughness. Equal Channel Angular Extrusion (ECAE) is proposed as a novel mechanism by which entanglements can be introduced to the polymer bulk during consolidation, with the aim of imparting the same tribological benefits of conventional processing without complete inhibition of chain motion. ECAE processing at temperatures near the crystalline melt for UHMWPE produces (1) increased entanglements compared to control materials; (2) increasing entanglements with increasing temperature; and (3) mechanical properties between values for untreated polyethylene and for cross-linked polyethylene. These results support additional research in ECAE-processed UHMWPE for joint arthroplasty applications. - Highlights: • A new processing method for ultra-high molecular weight polyethylene is introduced. • The process produces a highly entangled polyethylene material. • Entanglements are hypothesized to enhance the wear resistance of polyethylene. • This process eliminates the trade-off between mechanical and wear properties.

  15. Color measurement of plastics - From compounding via pelletizing, up to injection molding and extrusion

    Science.gov (United States)

    Botos, J.; Murail, N.; Heidemeyer, P.; Kretschmer, K.; Ulmer, B.; Zentgraf, T.; Bastian, M.; Hochrein, T.

    2014-05-01

    The typical offline color measurement on injection molded or pressed specimens is a very expensive and time-consuming process. In order to optimize the productivity and quality, it is desirable to measure the color already during the production. Therefore several systems have been developed to monitor the color e.g. on melts, strands, pellets, the extrudate or injection molded part already during the process. Different kinds of inline, online and atline methods with their respective advantages and disadvantages will be compared. The criteria are e.g. the testing time, which ranges from real-time to some minutes, the required calibration procedure, the spectral resolution and the final measuring precision. The latter ranges between 0.05 to 0.5 in the CIE L*a*b* system depending on the particular measurement system. Due to the high temperatures in typical plastics processes thermochromism of polymers and dyes has to be taken into account. This effect can influence the color value in the magnitude of some 10% and is barely understood so far. Different suitable methods to compensate thermochromic effects during compounding or injection molding by using calibration curves or artificial neural networks are presented. Furthermore it is even possible to control the color during extrusion and compounding almost in real-time. The goal is a specific developed software for adjusting the color recipe automatically with the final objective of a closed-loop control.

  16. Cervical artificial disc extrusion after a paragliding accident

    OpenAIRE

    Niu, Tianyi; Hoffman, Haydn; Lu, Daniel C.

    2017-01-01

    Background: Cervical total disc replacement (TDR) is an established alternative to anterior cervical discectomy and fusion (ACDF) with excellent long-term outcomes and low failure rates. Cases of implant failure and migration are scarce and primarily limited to several years postoperatively. The authors report a case of anterior extrusion of a C4-C5 ProDisc-C (DePuy Synthes, West Chester, PA, USA) cervical artificial disc (CAD) 14 months after placement due to minor trauma. Case Description: ...

  17. A bandage contact lens prevents extrusion of ocular contents.

    Science.gov (United States)

    Ramjiani, Vipul; Fearnley, Thomas; Tan, Jennifer

    2016-02-01

    A 76 year old male presents with a corneal perforation in a phthisical eye. Definitive treatment in the form of an evisceration was delayed by 38 days. During this period a bandage contact lens prevented extrusion of ocular contents through an enlarging corneal perforation. This case demonstrates that a bandage contact lens can be effective in the immediate management of large corneal perforations whilst awaiting urgent definitive treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Application of Electrostatic Extrusion – Flavour Encapsulation and Controlled Release

    OpenAIRE

    Manojlovic, Verica; Rajic, Nevenka; Djonlagic, Jasna; Obradovic, Bojana; Nedovic, Viktor; Bugarski, Branko

    2008-01-01

    The subject of this study was the development of flavour alginate formulations aimed for thermally processed foods. Ethyl vanilline was used as the model flavour compound. Electrostatic extrusion was applied for the encapsulation of ethyl vanilline in alginate gel microbeads. The obtained microbeads with approx. 10 % w/w of ethyl vanilline encapsulated in about 2 % w/w alginate were uniformly sized spheres of about 450 ?m. Chemical characterization by H-NMR spectroscopy revealed that the algi...

  19. Modelling Hot Air Balloons.

    Science.gov (United States)

    Brimicombe, M. W.

    1991-01-01

    A macroscopic way of modeling hot air balloons using a Newtonian approach is presented. Misleading examples using a car tire and the concept of hot air rising are discussed. Pressure gradient changes in the atmosphere are used to explain how hot air balloons work. (KR)

  20. Cervical artificial disc extrusion after a paragliding accident.

    Science.gov (United States)

    Niu, Tianyi; Hoffman, Haydn; Lu, Daniel C

    2017-01-01

    Cervical total disc replacement (TDR) is an established alternative to anterior cervical discectomy and fusion (ACDF) with excellent long-term outcomes and low failure rates. Cases of implant failure and migration are scarce and primarily limited to several years postoperatively. The authors report a case of anterior extrusion of a C4-C5 ProDisc-C (DePuy Synthes, West Chester, PA, USA) cervical artificial disc (CAD) 14 months after placement due to minor trauma. A 33-year-old female who had undergone C4-C5 CAD implantation presented with neck pain and spasm after experiencing a paragliding accident. A 4 mm anterior protrusion of the CAD was seen on x-ray. She underwent removal of the CAD followed by anterior fusion. Other cases of CAD extrusion in the literature are discussed and the device's durability and testing are considered. Overall, CAD extrusion is a rare event. This case is likely the result of insufficient osseous integration. Patients undergoing cervical TDR should avoid high-risk activities to prevent trauma that could compromise the disc's placement, and future design/research should focus on how to enhance osseous integration at the interface while minimizing excessive heterotopic ossification.

  1. Reduction of Fumonisin Toxicity by Extrusion and Nixtamalization (Alkaline Cooking).

    Science.gov (United States)

    Voss, Kenneth; Ryu, Dojin; Jackson, Lauren; Riley, Ronald; Gelineau-van Waes, Janee

    2017-08-23

    Fumonisins are mycotoxins found in corn. They are toxic to animals and cause cancer in rodents and neural tube defects in LM/Bc mice. Reducing their concentrations in corn-based foods is therefore desirable. Chemical analysis or in vitro bioassays of food extracts might not detect toxic fumonisin reaction products that are unknown or unextractable from food matrices, thus potentially underestimating in vivo toxicity. The effectiveness of two common cooking methods, extrusion and nixtamalization (alkaline cooking), to reduce the toxicity of fumonisin-contaminated corn grits (extrusion) and whole kernel corn (nixtamalization) was shown by means of rat feeding bioassays using fumonisin-specific kidney effects as indicators of potential toxicity. A third bioassay showed that in contrast to fumonisin B 1 (FB 1 ), hydrolyzed fumonisin B 1 (HFB 1 ; formed from FB 1 during nixtamalization) did not cause neural tube defects in LM/Bc mice. The findings indicate that extrusion and nixtamalization reduce the potential toxicity of FB 1 -contaminated corn.

  2. Preventing Silicone Tube Extrusion after Nasolacrimal Duct Intubation in Children

    Directory of Open Access Journals (Sweden)

    Ali-Akbar Sabermoghaddam

    2010-01-01

    Full Text Available Herein we report our experience with a simple technique for reducing the rate of silicone tube extrusion after nasolacrimal duct (NLD intubation for congenital NLD obstruction. Medical records of children older than 2 years, with or without history of failed probing, who had undergone NLD intubation with a Crawford silicone tube over a period of 4 years were reviewed. In all subjects, one end of the Crawford tube was passed through a piece of scalp vein tubing followed by applying one or two knots. All Crawford tubes were removed after 3 months. Main outcome measures included complications such as tube extrusion, nasal discharge, crust formation and pyogenic granuloma formation. Fifty-seven patients, including 49 unilateral and 8 bilateral cases with mean age of 3.8΁1.6 (range, 2 to 11.5 years were operated. No complications such as tube dislodgement, significant nasal discharge, crust or pyogenic granuloma formation occurred prior to Crawford tube removal. All silicone tubes were successfully removed from the nasal cavity. In conclusion, passing one end of the Crawford tube through a small piece of scalp vein tubing before knotting it in the nasal cavity seems to decrease the rate of tube extrusion which is the most common complication following NLD intubation in children.

  3. The Energetics and Physiological Impact of Cohesin Extrusion.

    Science.gov (United States)

    Vian, Laura; Pękowska, Aleksandra; Rao, Suhas S P; Kieffer-Kwon, Kyong-Rim; Jung, Seolkyoung; Baranello, Laura; Huang, Su-Chen; El Khattabi, Laila; Dose, Marei; Pruett, Nathanael; Sanborn, Adrian L; Canela, Andres; Maman, Yaakov; Oksanen, Anna; Resch, Wolfgang; Li, Xingwang; Lee, Byoungkoo; Kovalchuk, Alexander L; Tang, Zhonghui; Nelson, Steevenson; Di Pierro, Michele; Cheng, Ryan R; Machol, Ido; St Hilaire, Brian Glenn; Durand, Neva C; Shamim, Muhammad S; Stamenova, Elena K; Onuchic, José N; Ruan, Yijun; Nussenzweig, Andre; Levens, David; Aiden, Erez Lieberman; Casellas, Rafael

    2018-05-17

    Cohesin extrusion is thought to play a central role in establishing the architecture of mammalian genomes. However, extrusion has not been visualized in vivo, and thus, its functional impact and energetics are unknown. Using ultra-deep Hi-C, we show that loop domains form by a process that requires cohesin ATPases. Once formed, however, loops and compartments are maintained for hours without energy input. Strikingly, without ATP, we observe the emergence of hundreds of CTCF-independent loops that link regulatory DNA. We also identify architectural "stripes," where a loop anchor interacts with entire domains at high frequency. Stripes often tether super-enhancers to cognate promoters, and in B cells, they facilitate Igh transcription and recombination. Stripe anchors represent major hotspots for topoisomerase-mediated lesions, which promote chromosomal translocations and cancer. In plasmacytomas, stripes can deregulate Igh-translocated oncogenes. We propose that higher organisms have coopted cohesin extrusion to enhance transcription and recombination, with implications for tumor development. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. Dimensional accuracy of aluminium extrusions in mechanical calibration

    Science.gov (United States)

    Raknes, Christian Arne; Welo, Torgeir; Paulsen, Frode

    2018-05-01

    Reducing dimensional variations in the extrusion process without increasing cost is challenging due to the nature of the process itself. An alternative approach—also from a cost perspective—is using extruded profiles with standard tolerances and utilize downstream processes, and thus calibrate the part within tolerance limits that are not achievable directly from the extrusion process. In this paper, two mechanical calibration strategies for the extruded product are investigated, utilizing the forming lines of the manufacturer. The first calibration strategy is based on global, longitudinal stretching in combination with local bending, while the second strategy utilizes the principle of transversal stretching and local bending of the cross-section. An extruded U-profile is used to make a comparison between the two methods using numerical analyses. To provide response surfaces with the FEA program, ABAQUS is used in combination with Design of Experiment (DOE). DOE is conducted with a two-level fractional factorial design to collect the appropriate data. The aim is to find the main factors affecting the dimension accuracy of the final part obtained by the two calibration methods. The results show that both calibration strategies have proven to reduce cross-sectional variations effectively form standard extrusion tolerances. It is concluded that mechanical calibration is a viable, low-cost alternative for aluminium parts that demand high dimensional accuracy, e.g. due to fit-up or welding requirements.

  5. Multidrug and toxin extrusion proteins as transporters of antimicrobial drugs.

    Science.gov (United States)

    Nies, Anne T; Damme, Katja; Schaeffeler, Elke; Schwab, Matthias

    2012-12-01

    Antimicrobial drugs are essential in the treatment of infectious diseases. A better understanding of transport processes involved in drug disposition will improve the predictability of drug-drug interactions with consequences for drug response. Multidrug And Toxin Extrusion (MATE; SLC47A) proteins are efflux transporters mediating the excretion of several antimicrobial drugs as well as other organic compounds into bile and urine, thereby contributing to drug disposition. This review summarizes current knowledge of the structural and molecular features of human MATE transporters including their functional role in drug transport with a specific focus on antimicrobial drugs. The PubMed database was searched using the terms "MATE1," "MATE-2K," "MATE2," "SLC47A1," "SLC47A2," and "toxin extrusion protein" (up to June 2012). MATE proteins have been recognized as important transporters mediating the final excretion step of cationic drugs into bile and urine. These include the antiviral drugs acyclovir, amprenavir, and ganciclovir, the antibiotics cephalexin, cephradine and levofloxacin, as well as the antimalarial agents chloroquine and quinine. It is therefore important to enhance our understanding of the role of MATEs in drug extrusion with particular emphasis on the functional consequences of genetic variants on disposition of these antimicrobial drugs.

  6. Melt cooling by bottom flooding: The experiment CometPC-H3. Ex-vessel core melt stabilization research

    International Nuclear Information System (INIS)

    Alsmeyer, H.; Cron, T.; Merkel, G.; Schmidt-Stiefel, S.; Tromm, W.; Wenz, T.

    2003-03-01

    The CometPC-H3 experiment was performed to investigate melt cooling by water addition to the bottom of the melt. The experiment was performed with a melt mass of 800 kg, 50% metal and 50% oxide, and 300 kW typical decay heat were simulated in the melt. As this was the first experiment after repair of the induction coil, attention was given to avoid overload of the induction coil and to keep the inductor voltage below critical values. Therefore, the height of the sacrificial concrete layer was reduced to 5 cm only, and the height of the porous concrete layers was also minimized to have a small distance and good coupling between heated melt and induction coil. After quite homogeneous erosion of the upper sacrificial concrete layer, passive bottom flooding started from the porous concrete after 220 s with 1.3 liter water/s. The melt was safely stopped, arrested and cooled. The porous, water filled concrete was only slightly attacked by the hot melt in the upper 25 mm of one sector of the coolant device. The peak cooling rate in the early contact phase of coolant water and melt was 4 MW/m 2 , and exceeded the decay heat by one order of magnitude. The cooling rate remarkably dropped, when the melt was covered by the penetrating water and a surface crust was formed. Volcanic eruptions from the melt during the solidification process were observed from 360 - 510 s and created a volcanic dome some 25 cm high, but had only minor effect on the generation of a porous structure, as the expelled melt solidified mostly with low porosity. Unfortunately, decay heat simulation in the melt was interrupted at 720 s by an incorrect safety signal, which excluded further investigation of the long term cooling processes. At that time, the melt was massively flooded by a layer of water, about 80 cm thick, and coolant water inflow was still 1 l/s. The melt had reached a stable situation: Downward erosion was stopped by the cooling process from the water filled, porous concrete layer. Top

  7. Emerging melt quality control solution technologies for aluminium melt

    Directory of Open Access Journals (Sweden)

    Arturo Pascual, Jr

    2009-11-01

    Full Text Available The newly developed “MTS 1500” Melt Treatment System is performing the specifi cally required melt treatment operations like degassing, cleaning, modification and/or grain refinement by an automated process in one step and at the same location. This linked process is saving time, energy and metal losses allowing - by automated dosage of the melt treatment agents - the production of a consistent melt quality batch after batch. By linking the MTS Metal Treatment System with sensors operating on-line in the melt, i.e., with a hydrogen sensor “Alspek H”, a fully automated control of parts of the process chain like degassing is possible. This technology does guarantee a pre-specifi ed and documented melt quality in each melt treatment batch. Furthermore, to ensure that castings are consistent and predictable there is a growing realization that critical parameters such as metal cleanliness must be measured prior to casting. There exists accepted methods for measuring the cleanliness of an aluminum melt but these can be both slow and costly. A simple, rapid and meaningful method of measuring and bench marking the cleanliness of an aluminum melt has been developed to offer the foundry a practical method of measuring melt cleanliness. This paper shows the structure and performance of the integrated MTS melt treatment process and documents achieved melt quality standards after degassing, cleaning, modifi cation and grain refi nement operations under real foundry conditions. It also provides an insight on a melt cleanliness measuring device “Alspek MQ” to provide foundry men better tools in meeting the increasing quality and tighter specifi cation demand from the industry.

  8. Hot Embossing for Whole Teflon Superhydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Jie Li

    2018-06-01

    Full Text Available In this paper, we report a simple fabrication process of whole Teflon superhydrophobic surfaces, featuring high-aspect-ratio (>20 nanowire structures, using a hot embossing process. An anodic aluminum oxide (AAO membrane is used as the embossing mold for the fabrication of high-aspect-ratio nanowires directly on a Teflon substrate. First, high-aspect-ratio nanowire structures of Teflon are formed by pressing a fluorinated ethylene propylene (FEP sheet onto a heated AAO membrane at 340 °C, which is above the melting point of FEP. Experimental results show that the heating time and aspect ratios of nanopores in the AAO mold are critical to the fidelity of the hot embossed nanowire structures. It has also been found that during the de-molding step, a large adhesive force between the AAO mold and the molded FEP greatly prolongs the length of nanowires. Contact angle measurements indicate that Teflon nanowires make the surface superhydrophobic. The reliability and robustness of superhydrophobicity is verified by a long-term (~6.5 h underwater turbulent channel flow test. After the first step of hot-embossing the Teflon nanowires, microstructures are further superimposed by repeating the hot embossing process, but this time with microstructured silicon substrates as micromolds and at a temperature lower than the melting temperature of the FEP. The results indicate that the hot embossing process is also an effective way to fabricate hierarchical micro/nanostructures of whole Teflon, which can be useful for applications of Teflon material, such as superhydrophobic surfaces.

  9. Comparisons of microstructures and texture and mechanical properties of magnesium alloy fabricated by compound extrusion and direct extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Hu, H.-J., E-mail: hhj@cqut.edu.cn [Chongqing University of Technology, Chongqing 400050 (China); PLA Chongqing Logistics Engineering College, 401311 (China); Ying, Y.-L. [Chongqing University of Technology, Chongqing 400050 (China); Ou, Z.-W. [PLA Chongqing Logistics Engineering College, 401311 (China); Wang, X.-Q. [The University of Alabama, Tuscaloosa, AL 35487 (United States)

    2017-05-17

    In this study, microstructure evolution, textures and mechanical properties of AZ61 magnesium alloy were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile tests. The samples were processed by a new compound extrusion (CE) which combines direct extrusion (DE) and two steps of equal channel anger extrusion (ECAE). The results show that CE process can refine the microstructure more effectively than the DE process. The CE-fabricated samples have a weaker texture (0002), and a more fine and homogeneous microstructures, which attributes to the additional two steps of ECAE in CE process. In CE process, twin dynamic recrystallization and rotational dynamic recrystallization occurred, which enhances the refinement of the grains and weakening of the texture. In addition, the samples fabricated by CE process display a higher tensile properties (yield strength, tensile strength and elongation) with an excellent balance of strength and tensile ductility. Based on this study, severe plastic deformation (SPD) techniques combining conventional DE and two steps ECAE into a single process are feasibility to improve the mechanical properties of AZ61 Mg alloy.

  10. Dysprosium-free melt-spun permanent magnets

    International Nuclear Information System (INIS)

    Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

    2014-01-01

    Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd 2 Fe 14 B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175–200 °C. (paper)

  11. Dysprosium-free melt-spun permanent magnets.

    Science.gov (United States)

    Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

    2014-02-12

    Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd2Fe14B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175-200 °C.

  12. Development of rheological characterization and twin-screw extrusion/spiral winding processing methods for functionally-graded tissue engineering scaffolds and characterization of cell/biomaterial interactions

    Science.gov (United States)

    Ozkan, Seher

    Tissue engineering involves the fabrication of biodegradable scaffolds, on which various types of cells are grown, to provide tissue constructs for tissue repair/regeneration. Native tissues have complex structures, with functions and properties changing spatially and temporally, and require special tailoring of tissue engineering scaffolds to allow mimicking of their complex elegance. The understanding of the rheological behavior of the biodegradable polymer and the thermo-mechanical history that the polymer experiences during processing is critical in fabricating scaffolds with appropriate microstructural distributions. This study has first focused on the rheological material functions of various gel-like fluids including biofluids and hydrogels, which can emulate the viscoelastic behavior of biofluids. Viscoplasticity and wall slip were recognized as key attributes of such systems. Furthermore, a new technology base involving twin-screw extrusion/spiral winding (TSESW) process was developed for the shaping of functionally-graded scaffolds. This novel scaffold fabrication technology was applied to the development of polycaprolactone (PCL) scaffolds, incorporated with tricalcium phosphate nanoparticles and various porogens in graded fashion. The protein encapsulation and controlled release capabilities of the TSESW process was also demonstrated by dispersing bovine serum albumin (BSA) protein into the PCL matrix. Effects of processing conditions and porosity distributions on compressive properties, surface topography, encapsulation efficiency, release profiles and the secondary structure of BSA were investigated. The PCL scaffolds were determined to be biocompatible, with the proliferation rates of human fetal osteoblast cells (hFOB) increasing with increasing porosity and decreasing concentration of TCP. BSA proteins were determined to be denatured to a greater extent with melt extrusion in the 80-100°C range (in comparison to wet extrusion using organic

  13. Influence of extrusion-cooking parameters on some quality aspects of precooked pasta-like products.

    Science.gov (United States)

    Wójtowicz, A; Mościcki, L

    2009-06-01

    The present article aims to evaluate some quality parameters and texture characteristics of precooked wheat pasta-like products. Using the methods for pasta and instant noodles the tested parameters were water absorption, starch gelatinization degree, cooking losses, and hardness. The texture profile was characterized using Zwick apparatus by cutting test with the head speed of 10 mm/min and expressed as hardness and firmness of hydrated products. SEM pictures were used to illustrate the internal structure of dry and cooked pasta-like products. Dough moisture content and process conditions influenced all tested quality parameters of the pasta-like products processed on a modified single screw extrusion-cooker TS-45 with L: D = 16: 1. Good organoleptical quality (notes higher than 4 in a 5-point scale) and firm texture were observed for common wheat flour pasta processed at 30% m.c. Hardness and firmness of hydrated products lowered with a longer hydration time in hot water. The firmest texture and low stickiness was observed for products with a highest starch gelatinization degree.

  14. Interfacial reaction between SiC and aluminium due to extrusion and heat treatment process

    International Nuclear Information System (INIS)

    Junaidah Jai; Fauzi Ismail; Samsiah Sulaiman; Patthi Hussain, Azmi Idris; Yoichi Murakoshi

    1999-01-01

    Chemical interaction between aluminium (Al) and silicon carbide (SiC) produces aluminium carbide (Al 4 C 3 ) which presents potential problems in the production and application of Al/SiC Metal Matrix Composit (MMC). The Al 4 C 3 formed can reduce material properties such as strength in the MMC. This research work investigates the interface reaction in Al 7075/SiC MMC made through hot extrusion process. Mixed Al 7075/SiC MMC powders were pressed at 300 degree C and extruded at 500 degree C, with a reduction ratio of 20:1. The extruded MMC was then heat-treated in air at various temperatures from 560 degree C, 600 degree C, 640 degree C, 700 degree C to 800 degree C in order to observe the interface reaction of the MMC materials. The heat-treated MMCs were then analyzed under the optical microscope, X-ray Diffraction (XRD) Spectroscope and Scanning Electron Microscope (SEM) with Energy Dispersive X-ray (EDAZ) attachment to observe the interface reaction within the MMCs. This investigation confirms there was interface reaction between SiC and aluminium

  15. Effect of hot pressing additives on the leachability of hot pressed sodium hydrous titanium oxide

    International Nuclear Information System (INIS)

    Valentine, T.M.; Sambell, R.A.J.

    1980-01-01

    Sodium hydrous titanium oxide is an ion exchange resin which can be used for immobilizing medium level waste (MLW) liquors. When hot pressed, it undergoes conversion to a ceramic. Three low melting point materials (borax, bismuth trioxide, and a mixture of PbO/CuO) were added to the (Na)HTiO and the effect that each of these had on aiding densification was assessed. Hot pressing temperature, applied pressure, and percentage addition of hot pressing aid were varied. Percentage open porosity, flexural strength, and leachability were measured. There was a linear relationship between the percentage open porosity and the logarithm of the leach rate for a constant percentage addition of each additive

  16. Flow of Polymer Melts in Plane- and Axi-symmetric Converging Dies

    DEFF Research Database (Denmark)

    Lauridsen, Carsten Linding; Kjær, Erik Michael; Haudrum, Jan

    1997-01-01

    The extensional flow has considerable influence on the pressure loss in converging flows, which are present in both extrusion and injection moulding. Both plane- and axi-symmetric converging flows have been studied with LDPE, HDPE and PS. The transient extensional viscosities are determined in al...... for the LDPE and the PS melts. Further more, the pressure losses are characterised with the Deborah number in which the characteristic time of the material is shear rate dependent and the characteristic rime of the now is Hencky strain rate dependent....

  17. Flow of Polymer Melts in Plane- and Axi-Symmetric Converging Dies

    DEFF Research Database (Denmark)

    Lauridsen, Carsten Linding; Kjær, Erik Michael; Haudrum, Jan

    1998-01-01

    The extensional flow has considerable influence on the pressure loss in converging flows, which are present in both extrusion and injection moulding. Both plane- and axi-symmetric converging flows have been studied with LDPE, HDPE and PS. The transient extensional viscosities are determined in al...... are comparable for the LDPE and the PS melts. Furthermore, the pressure losses are characterized with the Deborah number in which the characteristic time of the material is shear rate dependent and the characteristic time of the flow is Hencky strain rate dependent....

  18. Use of a high temperature hydrostatic extrusion technique for powders strengthening

    International Nuclear Information System (INIS)

    Decours, J.; Gavinet, J.; Weisz, M.

    1975-01-01

    A conventional 575 tonnes extrusion press has been modified by a device permitting the extrusion process by hydrostatic pression through a leakless mechanical set (13,000 bars maximum), from room temperature to 1,200 deg C. This new device allows: the high temperature hydrostatic extrusion for strengthening of powders, the isostatic compression of powders. Examples of realisations obtained by this process are described, including the influence of different parameters: pressure, temperature, extrusion ratio and for different materials: pure metals (iron, nickel, niobium, etc...) and alloys (stainless steel, molybdenum, niobium nickel alloys, etc...). Then, the advantages of the process are emphasized [fr

  19. Method of melting solid waste

    International Nuclear Information System (INIS)

    Ootsuka, Katsuyuki; Mizuno, Ryokichi; Kuwana, Katsumi; Sawada, Yoshihisa; Komatsu, Fumiaki.

    1982-01-01

    Purpose: To enable the volume reduction treatment of a HEPA filter containing various solid wastes, particularly acid digestion residue, or an asbestos separator at a relatively low temperature range. Method: Solid waste to be heated and molten is high melting point material treated by ''acid digestion treatment'' for treating solid waste, e.g. a HEPA filter or polyvinyl chloride, etc. of an atomic power facility treated with nitric acid or the like. When this material is heated and molten by an electric furnace, microwave melting furnace, etc., boron oxide, sodium boride, sodium carbonate, etc. is added as a melting point lowering agent. When it is molten in this state, its melting point is lowered, and it becomes remarkably fluid, and the melting treatment is facilitated. Solidified material thus obtained through the melting step has excellent denseness and further large volume reduction rate of the solidified material. (Yoshihara, H.)

  20. Petrological Geodynamics of Mantle Melting II. AlphaMELTS + Multiphase Flow: Dynamic Fractional Melting

    Science.gov (United States)

    Tirone, Massimiliano

    2018-03-01

    In this second installment of a series that aims to investigate the dynamic interaction between the composition and abundance of the solid mantle and its melt products, the classic interpretation of fractional melting is extended to account for the dynamic nature of the process. A multiphase numerical flow model is coupled with the program AlphaMELTS, which provides at the moment possibly the most accurate petrological description of melting based on thermodynamic principles. The conceptual idea of this study is based on a description of the melting process taking place along a 1-D vertical ideal column where chemical equilibrium is assumed to apply in two local sub-systems separately on some spatial and temporal scale. The solid mantle belongs to a local sub-system (ss1) that does not interact chemically with the melt reservoir which forms a second sub-system (ss2). The local melt products are transferred in the melt sub-system ss2 where the melt phase eventually can also crystallize into a different solid assemblage and will evolve dynamically. The main difference with the usual interpretation of fractional melting is that melt is not arbitrarily and instantaneously extracted from the mantle, but instead remains a dynamic component of the model, hence the process is named dynamic fractional melting (DFM). Some of the conditions that may affect the DFM model are investigated in this study, in particular the effect of temperature, mantle velocity at the boundary of the mantle column. A comparison is made with the dynamic equilibrium melting (DEM) model discussed in the first installment. The implications of assuming passive flow or active flow are also considered to some extent. Complete data files of most of the DFM simulations, four animations and two new DEM simulations (passive/active flow) are available following the instructions in the supplementary material.

  1. Experimental study of simulant melt stream-water thermal interaction in pool and narrow geometries

    International Nuclear Information System (INIS)

    Narayanan, K.S.; Jasmin Sudha, A.; Murthy, S.S.; Rao, E.H.V.M.; Lydia, G.; Das, S.K.; Harvey, J.; Kannan, S.E.

    2005-01-01

    Full text of publication follows: Small scale experiments were carried out to investigate the thermal interaction characteristics of a few kilograms of Sn Pb, Bi and Zn as hot melt, in the film boiling region of water in an attempt to simulate a coherent fuel coolant interaction during a postulated severe accident in a nuclear reactor. Melt stream solidification and detached debris generation were studied with different melt superheat up to 200 deg. C, at different coolant temperatures of 30 deg. C, 50 deg. C, 70 deg. C, 90 deg. C, in pool geometry and in long narrow coolant column. The material was heated in an Alumina crucible and poured through a hot stainless steel funnel with a nozzle diameter of 7.7 mm, into the coolant. A stainless steel plate was used to collect the solidified mass after the interaction. Temperature monitoring was done in the coolant column close to the melt stream. The melt stream movement inside the coolant was imaged using a video camera at 25 fps. Measured melt stream entry velocity was around 1.5 m/sec. For low melt superheat and low coolant temperature, solidified porous tree like structure extended from the collector plate up to the melt release point. For water temperature of 70 deg. C, the solidified bed height at the center was found to decrease with increase in the melt superheat up to 150 deg. C. Fragmentation was found to occur when the melt superheat exceeded 200 deg. C. Particle size distribution was obtained for the fragmented debris. In 1D geometry, with 50 deg. C superheat, columnar solidification was observed with no fine debris. The paper gives the details of the results obtained in the experiments and highlights the role of Rayleigh-Taylor, Kelvin-Helmholtz instabilities and the melt physical properties on the fragmentation kinetics. (authors)

  2. Logistics Reduction: Heat Melt Compactor

    Data.gov (United States)

    National Aeronautics and Space Administration — The Advanced Exploration Systems (AES) Logistics Reduction (LR) project Heat Melt Compactor (HMC) technology is a waste management technology. Currently, there are...

  3. Melting in trivalent metal chlorides

    International Nuclear Information System (INIS)

    Saboungi, M.L.; Price, D.L.; Scamehorn, C.; Tosi, M.P.

    1990-11-01

    We report a neutron diffraction study of the liquid structure of YCl 3 and combine the structural data with macroscopic melting and transport data to contrast the behaviour of this molten salt with those of SrCl 2 , ZnCl 2 and AlCl 3 as prototypes of different melting mechanisms for ionic materials. A novel melting mechanism for trivalent metal chlorides, leading to a loose disordered network of edge-sharing octahedral units in the liquid phase, is thereby established. The various melting behaviours are related to bonding character with the help of Pettifor's phenomenological chemical scale. (author). 25 refs, 4 figs, 3 tabs

  4. Melting of contaminated metallic waste

    International Nuclear Information System (INIS)

    Lee, Y.-S.; Cheng, S.-Y.; Kung, H.-T.; Lin, L.-F.

    2004-01-01

    Approximately 100 tons of contaminated metallic wastes were produced each year due to maintenance for each TPC's nuclear power reactor and it was roughly estimated that there will be 10,000 tons of metallic scraps resulted from decommissioning of each reactor in the future. One means of handling the contaminated metal is to melt it. Melting process owns not only volume reduction which saves the high cost of final disposal but also resource conservation and recycling benefits. Melting contaminated copper and aluminum scraps in the laboratory scale have been conducted at INER. A total of 546 kg copper condenser tubes with a specific activity of about 2.7 Bq/g was melted in a vacuum induction melting facility. Three types of products, ingot, slag and dust were derived from the melting process, with average activities of 0.10 Bq/g, 2.33 Bq/g and 84.3 Bq/g respectively. After the laboratory melting stage, a pilot plant with a 500 kg induction furnace is being designed to melt the increasingly produced contaminated metallic scraps from nuclear facilities and to investigate the behavior of different radionuclides during melting. (author)

  5. Direct Coupling of Electron Beam Irradiation and Polymer Extrusion for a Continuous Polymer Modification in Molten State

    International Nuclear Information System (INIS)

    Stephan, M.

    2006-01-01

    The new approach of an e-beam initiating of chemical reactions in polymers in molten state results in some innovative results. High temperature, intensive macromolecular mobility and the absence of any crystallinity are some reasons for achieving unexpected structures, processing behaviour and properties changes in such treated thermoplastics and rubbers. Examples are a much more effective crosslinking of polyethylene and special rubbers, long chain branching of polypropylene or a partial crosslinking of polysulfone. Additionally, most of these modification effects are also achievable by a direct coupling of electron beam irradiation and conventional polymer extrusion processing for a continuous polymer modification in molten state. For realizing this unique processing technique a special MOBILE RADIATION FACILITY (MOBRAD1/T) was designed, constructed and manufactured in the IPF Dresden at which a lab-scale single screw extruder was adapted direct to an electron beam accelerator to realize a prompt irradiation of extruded polymer melt profiles before there solidification. Surprisingly, as a result of these short-time-melt reactions some effective and new polymer modification effects were found and will be presented

  6. Microemulsion extrusion technique: a new method to produce lipid nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Marcelo Bispo de, E-mail: dejesusmb@gmail.com; Radaic, Allan [University of Campinas-UNICAMP, Department of Biochemistry, Institute of Biology (Brazil); Zuhorn, Inge S. [University of Groningen, Department of Membrane Cell Biology, University Medical Center (Netherlands); Paula, Eneida de [University of Campinas-UNICAMP, Department of Biochemistry, Institute of Biology (Brazil)

    2013-10-15

    Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been intensively investigated for different applications, including their use as drug and gene delivery systems. Different techniques have been employed to produce lipid nanoparticles, of which high pressure homogenization is the standard technique that is adopted nowadays. Although this method has a high efficiency, does not require the use of organic solvents, and allows large-scale production, some limitations impede its application at laboratory scale: the equipment is expensive, there is a need of huge amounts of surfactants and co-surfactants during the preparation, and the operating conditions are energy intensive. Here, we present the microemulsion extrusion technique as an alternative method to prepare lipid nanoparticles. The parameters to produce lipid nanoparticles using microemulsion extrusion were established, and the lipid particles produced (SLN, NLC, and liposomes) were characterized with regard to size (from 130 to 190 nm), zeta potential, and drug (mitoxantrone) and gene (pDNA) delivery properties. In addition, the particles' in vitro co-delivery capacity (to carry mitoxantrone plus pDNA encoding the phosphatase and tensin homologue, PTEN) was tested in normal (BALB 3T3 fibroblast) and cancer (PC3 prostate and MCF-7 breast) cell lines. The results show that the microemulsion extrusion technique is fast, inexpensive, reproducible, free of organic solvents, and suitable for small volume preparations of lipid nanoparticles. Its application is particularly interesting when using rare and/or costly drugs or ingredients (e.g., cationic lipids for gene delivery or labeled lipids for nanoparticle tracking/diagnosis)

  7. Role of lipids in the extrusion cooking processes

    Directory of Open Access Journals (Sweden)

    Berghofe, E.

    2000-04-01

    Full Text Available Extrusion is a versatile and very efficient technology that is widely used in food and feed processing. The cooking extruders have found many applications, which include: breakfast cereals, snack foods, other cereal based products, pet food and aquatic foods, texturized vegetable proteins, confectionery products, chemical and biochemical reactions, and oil extraction. Lipids are components that play an important role in most of the extrusion cooking processes. They can act as plastificizers or emulsifiers, and affect more significantly texture and stickiness of the extrudate. This paper reviews effect of oils and other lipids reactions during extrusion cooking as well as the effects of amylase-lipid complexation on extrudate quality.La extrusión es, en general, una tecnología versátil y muy eficiente, que se aplica ampliamente en la elaboración de alimentos y piensos. Los equipos de cocción-extrusión tienen numerosas aplicaciones, entre las que pueden incluirse: los cereales de desayuno listos para comer, los aperitivos, diferentes productos basados en cereales, los piensos para animales domésticos y peces, proteínas vegetales texturizadas, productos de pastelería, reacciones químicas y bioquímicas, y la extracción de aceites. Los lípidos son componentes que juegan un papel importante en la mayoría de los procesos de cocción-extrusión. Pueden actuar como plastificantes o como emulsionantes, suministrando lubricación. En este artículo se revisan con detalle los efectos de las reacciones de los aceites y otros lípidos durante el proceso de cocción-extrucción así como el efecto de la formación de complejos amilasa-lípidos sobre la calidad de los extrudados.

  8. Distal corporoplasty for distal cylinders extrusion after penile prosthesis implantation.

    Science.gov (United States)

    Carrino, Maurizio; Chiancone, Francesco; Battaglia, Gaetano; Pucci, Luigi; Fedelini, Paolo

    2017-02-03

    Distal extrusion of cylinders is a potential complication of the penile prosthesis implantation. Several methods have been proposed for repairing a distal penile erosion. We present our preliminary experience in "Distal corporoplasty" technique. We enrolled 18 consecutive patients whose underwent a distal corporoplasty with simultaneous reimplantation of an "AMS 700 inflatable penile prosthesis (LGX)" from January 2013 to November 2015 at our hospital. All procedures were performed by a single surgical team. Intraoperative and postoperative complications have been classified and reported according to Satava6 and Clavien-Dindo (CD) system.7 Mean values with standard deviations (±SD) were computed and reported for all items. Mean age of the patients was 53.61 (±11.90) years. Mean body max index (BMI) was 24.22 (±2.51). Mean operative time was 85.2 (±13.1) minutes. Blood losses were minimal. No intraoperative complications are reported according to Satava classification. Four out of 18 patients (22.22%) experienced postoperative complications according to CD system. All patients had sexual intercourse for the first time postsurgery after a mean of 59.11 ± 2.08 days. Mean follow-up was 22.11 (±9.95). Distal extrusion of cylinders is a potential complication of the penile prosthesis implantation. Distal corporoplasty was first described by Mulcahy. He reported a series of 14 patients with a follow-up of about 2 years with optimal functional outcomes. Moreover, distal corporoplasty resulted in shorter operative time, better function, less pain, and fewer recurrences than Gortex windsock repair.10 In our experience, distal corporoplasty is a simple and safe procedure in the treatment of distal cylinders extrusion when the prosthetic material is not exposed to the exterior.

  9. Microemulsion extrusion technique: a new method to produce lipid nanoparticles

    International Nuclear Information System (INIS)

    Jesus, Marcelo Bispo de; Radaic, Allan; Zuhorn, Inge S.; Paula, Eneida de

    2013-01-01

    Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been intensively investigated for different applications, including their use as drug and gene delivery systems. Different techniques have been employed to produce lipid nanoparticles, of which high pressure homogenization is the standard technique that is adopted nowadays. Although this method has a high efficiency, does not require the use of organic solvents, and allows large-scale production, some limitations impede its application at laboratory scale: the equipment is expensive, there is a need of huge amounts of surfactants and co-surfactants during the preparation, and the operating conditions are energy intensive. Here, we present the microemulsion extrusion technique as an alternative method to prepare lipid nanoparticles. The parameters to produce lipid nanoparticles using microemulsion extrusion were established, and the lipid particles produced (SLN, NLC, and liposomes) were characterized with regard to size (from 130 to 190 nm), zeta potential, and drug (mitoxantrone) and gene (pDNA) delivery properties. In addition, the particles’ in vitro co-delivery capacity (to carry mitoxantrone plus pDNA encoding the phosphatase and tensin homologue, PTEN) was tested in normal (BALB 3T3 fibroblast) and cancer (PC3 prostate and MCF-7 breast) cell lines. The results show that the microemulsion extrusion technique is fast, inexpensive, reproducible, free of organic solvents, and suitable for small volume preparations of lipid nanoparticles. Its application is particularly interesting when using rare and/or costly drugs or ingredients (e.g., cationic lipids for gene delivery or labeled lipids for nanoparticle tracking/diagnosis)

  10. Hot Surface Ignition

    OpenAIRE

    Tursyn, Yerbatyr; Goyal, Vikrant; Benhidjeb-Carayon, Alicia; Simmons, Richard; Meyer, Scott; Gore, Jay P.

    2015-01-01

    Undesirable hot surface ignition of flammable liquids is one of the hazards in ground and air transportation vehicles, which primarily occurs in the engine compartment. In order to evaluate the safety and sustainability of candidate replacement fuels with respect to hot surface ignition, a baseline low lead fuel (Avgas 100 LL) and four experimental unleaded aviation fuels recommended for reciprocating aviation engines were considered. In addition, hot surface ignition properties of the gas tu...

  11. Melting method for miscellaneous radioactive solid waste and melting furnace

    International Nuclear Information System (INIS)

    Osaki, Toru; Furukawa, Hirofumi; Uda, Nobuyoshi; Katsurai, Kiyomichi

    1998-01-01

    A vessel containing miscellaneous solid wastes is inserted in a crucible having a releasable material on the inner surface, they are induction-heated from the outside of the crucible by way of low temperature heating coils to melt low melting point materials in the miscellaneous wastes within a temperature range at which the vessel does not melt. Then, they are induction-heated by way of high temperature heating coils to melt the vessel and not yet melted materials, those molten materials are cooled, solidified molten material and the releasable material are taken out, and then the crucible is used again. Then, the crucible can be used again, so that it can be applied to a large scaled melting furnace which treats wastes by a unit of drum. In addition, since the cleaning of the used crucible and the application of the releasable material can be conducted without interrupting the operation of the melting furnace, the operation cycle of the melting furnace can be shortened. (N.H.)

  12. [Technique for removing donor sclera by eyeball extrusion].

    Science.gov (United States)

    González Del Valle, F; Álvarez Portela, M; Lara Medina, J; Celis Sánchez, J; Barrajón Rodríguez, A

    2012-09-01

    To describe a surgery technique for removing donor sclera tissue after corneo-scleral button excision. The extrusion technique is easy to perform. It allows the complete scleral extraction its total clean up to be performed, as well as making easier to isolate the retina and uveal tissue. This technique could have an important role in the anatomical and morphological study of ocular structures. Copyright © 2011 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  13. The role of extrusions and intrusions in fatigue crack initiation

    Czech Academy of Sciences Publication Activity Database

    Polák, Jaroslav; Mazánová, Veronika; Heczko, Milan; Petráš, Roman; Kuběna, Ivo; Casalena, L.; Man, Jiří

    2017-01-01

    Roč. 185, NOV (2017), s. 46-60 ISSN 0013-7944 R&D Projects: GA MŠk(CZ) LQ1601; GA MŠk LM2015069; GA ČR(CZ) GA13-23652S; GA ČR GA15-08826S Institutional support: RVO:68081723 Keywords : Extrusion * Fatigue crack initiation * Intrusion * Persistent slip marking * Stainless steel Subject RIV: JL - Materials Fatigue, Friction Mechanics OBOR OECD: Audio engineering, reliability analysis Impact factor: 2.151, year: 2016

  14. Waste glass melting stages

    International Nuclear Information System (INIS)

    Anderson, L.D.; Dennis, T.; Elliott, M.L.; Hrma, P.

    1994-01-01

    Three simulated nuclear waste glass feeds, consisting of dried waste and glass frit, were heat treated for 1 hour in a gradient furnace at temperatures ranging from approximately 600 degrees C to 1000 degrees C. Simulated melter feeds from the Hanford Waste Vitrification Plant (HWVP), the Defense Waste Processing Facility (DWPF), and Kernforschungszentru Karlsruhe (KfK) in Germany were used. The samples were thin sectioned and examined by optical microscopy to investigate the stages of the conversion from feed to glass. Various phenomena were seen, such as frit softening, bubble formation, foaming, bubble motion and removal, convective mixing, and homogenization. The behavior of different feeds was similar, although the degree of gas generation and melt homogenization varied. 2 refs., 8 tabs

  15. Waste glass melting stages

    International Nuclear Information System (INIS)

    Anderson, L.D.; Dennis, T.; Elliott, M.L.; Hrma, P.

    1993-04-01

    Three different simulated nuclear waste glass feeds, consisting of dried waste and glass frit, were heat treated for 1 hour in a gradient furnace at temperatures ranging from approximately 600 degrees C--1000 degrees C. Simulated melter feeds from the Hanford Waste Vitrification Plant (HWVP), the Defense Waste Processing Facility (DWPF), and Kernforschungszentrum Karlsruhe (KfK) in Germany were used. The samples were thin-sectioned and examined by optical microscopy to investigate the stages of the conversion from feed to glass. Various phenomena were seen, such as frit softening, bubble formation, foaming, bubble motion and removal, convective mixing, and homogenization. Behavior of different feeds was similar, although the degree of gas generation and melt homogenization varied

  16. Rhenium corrosion in chloride melts

    International Nuclear Information System (INIS)

    Stepanov, A.D.; Shkol'nikov, S.N.; Vetyukov, M.M.

    1989-01-01

    The results investigating rhenium corrosion in chloride melts containing sodium, potassium and chromium ions by a gravimetry potentials in argon atmosphere in a sealing quarth cell are described. Rhenium corrosion is shown to be rather considerable in melts containing CrCl 2 . The value of corrosion rate depending on temperature is determined

  17. UNCONSTRAINED MELTING AND SOLIDIFICATION INSIDE ...

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... There is a large number of experimental and numerical works on melting and solidification of PCM[6-10], and also its usage as thermal management in building [11-14], electronic devices [15-16] and solar energy. [17-20].Most investigated geometries in melting and freezing process are sphere (spherical.

  18. Optimization of extrusion process for production of nutritious pellets

    Directory of Open Access Journals (Sweden)

    Ernesto Aguilar-Palazuelos

    2012-03-01

    Full Text Available A blend of 50% Potato Starch (PS, 35% Quality Protein Maize (QPM, and 15% Soybean Meal (SM were used in the preparation of expanded pellets utilizing a laboratory extruder with a 1.5 × 20.0 × 100.0 mm die-nozzle. The independent variables analyzed were Barrel Temperature (BT (75-140 °C and Feed Moisture (FM (16-30%. The effect of extrusion variables was investigated in terms of Expansion Index (EI, apparent density (ApD, Penetration Force (PF and Specific Mechanical Energy (SME, viscosity profiles, DSC, crystallinity by X-ray diffraction, and Scanning Electronic Microscopy (SEM. The PF decreased from 30 to 4 kgf with the increase of both independent variables (BT and FM. SME was affected only by FM, and decreased with the increase in this variable. The optimal region showed that the maximum EI was found for BT in the range of 123-140 °C and 27-31% for FM, respectively. The extruded pellets obtained from the optimal processing region were probably not completely degraded, as shown in the structural characterization. Acceptable expanded pellets could be produced using a blend of PS, QPM, and SM by extrusion cooking.

  19. Extrusion Bioprinting of Shear-Thinning Gelatin Methacryloyl Bioinks.

    Science.gov (United States)

    Liu, Wanjun; Heinrich, Marcel A; Zhou, Yixiao; Akpek, Ali; Hu, Ning; Liu, Xiao; Guan, Xiaofei; Zhong, Zhe; Jin, Xiangyu; Khademhosseini, Ali; Zhang, Yu Shrike

    2017-06-01

    Bioprinting is an emerging technique for the fabrication of 3D cell-laden constructs. However, the progress for generating a 3D complex physiological microenvironment has been hampered by a lack of advanced cell-responsive bioinks that enable bioprinting with high structural fidelity, particularly in the case of extrusion-based bioprinting. Herein, this paper reports a novel strategy to directly bioprint cell-laden gelatin methacryloyl (GelMA) constructs using bioinks of GelMA physical gels (GPGs) achieved through a simple cooling process. Attributed to their shear-thinning and self-healing properties, the GPG bioinks can retain the shape and form integral structures after deposition, allowing for subsequent UV crosslinking for permanent stabilization. This paper shows the structural fidelity by bioprinting various 3D structures that are typically challenging to fabricate using conventional bioinks under extrusion modes. Moreover, the use of the GPG bioinks enables direct bioprinting of highly porous and soft constructs at relatively low concentrations (down to 3%) of GelMA. It is also demonstrated that the bioprinted constructs not only permit cell survival but also enhance cell proliferation as well as spreading at lower concentrations of the GPG bioinks. It is believed that such a strategy of bioprinting will provide many opportunities in convenient fabrication of 3D cell-laden constructs for applications in tissue engineering, regenerative medicine, and pharmaceutical screening. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Analysis on dynamic tensile extrusion behavior of UFG OFHC Cu

    Science.gov (United States)

    Park, Kyung-Tae; Park, Leeju; Kim, Hak Jun; Kim, Seok Bong; Lee, Chong Soo

    2014-08-01

    Dynamic tensile extrusion (DTE) tests with the strain rate order of ~105 s-1 were conducted on coarse grained (CG) Cu and ultrafine grained (UFG) Cu. ECAP of 16 passes with route Bc was employed to fabricate UFG Cu. DTE tests were carried out by launching the sphere samples to the conical extrusion die at a speed of ~475 m/sec in a vacuumed gas gun system. UFG Cu was fragmented into 3 pieces and showed a DTE elongation of ~340%. CG Cu exhibited a larger DTE elongation of ~490% with fragmentation of 4 pieces. During DTE tests, dynamic recrystallization occurred in UFG Cu, but not in CG Cu. In order to examine the DTE behavior of CG Cu and UFG Cu under very high strain rates, a numerical analysis was undertaken by using a commercial finite element code (LS-DYNA 2D axis-symmetric model) with the Johnson - Cook model. The numerical analysis correctly predicted fragmentation and DTE elongation of CG Cu. But, the experimental DTE elongation of UFG Cu was much smaller than that predicted by the numerical analysis. This difference is discussed in terms of microstructural evolution of UFG Cu during DTE tests.

  1. Machine for extrusion under vacuum; Machine de fluage sous vide

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    In a study of the behaviour of easily oxidised metals during the extrusion process, it is first necessary to find an effective mean of fighting corrosion, since this, even when barely detectable, has an important influence on the validity of the results recorded. The neatest and also the most efficient of all the methods tried consists in creating a vacuum around the test piece. Working on this principle, and at the same time respecting the conventional rules for extrusion tests (loading the sample after stabilisation at the testing temperature, differential measurements of lengthening, etc.) we found it necessary to construct an original machine. (author) [French] L'etude du comportement au fluage des materiaux facilement oxydables exige, en premier lieu, une lutte efficace contre la corrosion qui, meme a peine decelable, prend une part preponderante quant a la validite des resultats enregistres. La solution la plus elegante, et, a vrai dire, la plus energique parmi toutes les methodes essayees, consiste a realiser le vide autour de l'eprouvette d'essai. Partant de ce principe, et pour sauvegarder les regles classiques de l'essai de fluage (mise en charge de l'eprouvette apres stabilisation en temperature d'essai, mesures differentielles des allongements, etc.) nous nous sommes trouves dans la necessite de construire une machine inedite. (auteur)

  2. Machine for extrusion under vacuum; Machine de fluage sous vide

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    In a study of the behaviour of easily oxidised metals during the extrusion process, it is first necessary to find an effective mean of fighting corrosion, since this, even when barely detectable, has an important influence on the validity of the results recorded. The neatest and also the most efficient of all the methods tried consists in creating a vacuum around the test piece. Working on this principle, and at the same time respecting the conventional rules for extrusion tests (loading the sample after stabilisation at the testing temperature, differential measurements of lengthening, etc.) we found it necessary to construct an original machine. (author) [French] L'etude du comportement au fluage des materiaux facilement oxydables exige, en premier lieu, une lutte efficace contre la corrosion qui, meme a peine decelable, prend une part preponderante quant a la validite des resultats enregistres. La solution la plus elegante, et, a vrai dire, la plus energique parmi toutes les methodes essayees, consiste a realiser le vide autour de l'eprouvette d'essai. Partant de ce principe, et pour sauvegarder les regles classiques de l'essai de fluage (mise en charge de l'eprouvette apres stabilisation en temperature d'essai, mesures differentielles des allongements, etc.) nous nous sommes trouves dans la necessite de construire une machine inedite. (auteur)

  3. Plasticized chitosan/polyolefin films produced by extrusion.

    Science.gov (United States)

    Matet, Marie; Heuzey, Marie-Claude; Ajji, Abdellah; Sarazin, Pierre

    2015-03-06

    Plasticized chitosan and polyethylene blends were produced through a single-pass extrusion process. Using a twin-screw extruder, chitosan plasticization was achieved in the presence of an acetic acid solution and glycerol, and directly mixed with metallocene polyethylene, mPE, to produce a masterbatch. Different dilutions of the masterbatch (2, 5 and 10 wt% of plasticized chitosan), in the presence of ethylene vinyl acetate, EVA, were subsequently achieved in single screw film extrusion. Very small plasticized chitosan domains (number average diameter <5 μm) were visible in the polymeric matrix. The resulting films presented a brown color and increasing haze with chitosan plasticized content. Mechanical properties of the mPE films were affected by the presence of plasticized chitosan, but improvement was observed as a result of some compatibility between mPE and chitosan in the presence of EVA. Finally the incorporation of plasticized chitosan affected mPE water vapor permeability while oxygen permeability remained constant. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Physical simulation method for the investigation of weld seam formation during the extrusion of aluminum alloys

    NARCIS (Netherlands)

    Fang, G; Zhou, J.

    2017-01-01

    Extrusion through the porthole die is a predominant forming process used in the production of hollow aluminum alloy profiles across the aluminum extrusion industry. Longitudinal weld seams formed during the process may negatively influence the quality of extruded profiles. It is therefore of

  5. 75 FR 22109 - Aluminum Extrusions from the People's Republic of China: Initiation of Antidumping Duty...

    Science.gov (United States)

    2010-04-27

    ... Aluminium, Ltd., a producer of aluminum extrusions, for the 2008 2009 fiscal year. See Volume II of the..., produced by an extrusion process, made from aluminum alloys having metallic elements corresponding to the alloy series designations published by The Aluminum Association commencing with the numbers 1, 3, and 6...

  6. Extrusion-cooking to improve the animal feed quality of broad beans

    NARCIS (Netherlands)

    Moscicki, L.; Wojcik, S.; Plaur, K.; Zuilichem, van D.J.

    1984-01-01

    Extrusion-cooking of broad beans with a single-screw extruder has been investigated. Attention was focused on process requirements as well as on the nutritional effects of extrusion-cooked broad beans in a chicken feed formulation. The optimal thermal process conditions required for a product of

  7. Periodontal healing complications following extrusive and lateral luxation in the permanent dentition: a longitudinal cohort study

    DEFF Research Database (Denmark)

    Hermann, Nuno Vibe; Lauridsen, Eva Fejerskov; Christensen, Søren Steno Ahrensburg

    2012-01-01

    To analyze the risk of tooth loss and complications in periodontal ligament (PDL) healing following extrusive and lateral luxation in the permanent dentition.......To analyze the risk of tooth loss and complications in periodontal ligament (PDL) healing following extrusive and lateral luxation in the permanent dentition....

  8. Physical properties, molecular structures and protein quality of texturized whey protein isolate: effect of extrusion temperature

    Science.gov (United States)

    Extrusion is a powerful food processing operation, which utilizes high temperature and high shear force to produce a product with unique physical and chemical characteristics. Texturization of whey protein isolate (WPI) through extrusion for the production of protein fortified snack foods has provid...

  9. Chemical, physical and nutritional changes in soybean meal as a result of toasting and extrusion cooking

    NARCIS (Netherlands)

    Marsman, G.J.P.

    1998-01-01

    The effect of soybean meal extrusion and the development of shear forces during single-screw extrusion was compared with the toasting process of soybean meal. Attention was focused on chemical, physical and nutritional changes during these thermo-mechanical

  10. Factors affecting irrigant extrusion during root canal irrigation: a systematic review

    NARCIS (Netherlands)

    Boutsioukis, C.; Psimma, Z.; van der Sluis, L.W.M.

    2013-01-01

    The aim of the present study was to conduct a systematic review and critical analysis of published data on irrigant extrusion to identify factors causing, affecting or predisposing to irrigant extrusion during root canal irrigation of human mature permanent teeth. An electronic search was conducted

  11. 78 FR 67115 - Aluminum Extrusions From the People's Republic of China: Intent To Rescind 2012 Countervailing...

    Science.gov (United States)

    2013-11-08

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-570-968] Aluminum Extrusions From the People's Republic of China: Intent To Rescind 2012 Countervailing Duty Administrative Review, in Part... administrative review of the countervailing duty (CVD) order on aluminum extrusions from the People's Republic of...

  12. Coupled analysis of material flow and die deflection in direct aluminum extrusion

    NARCIS (Netherlands)

    Assaad, W.; Geijselaers, Hubertus J.M.

    2010-01-01

    The design of extrusion dies depends on the experience of the designer. After the die has been manufactured, it is tested during an extrusion trial and machined several times until it works properly. The die is designed by a trial and error method which is an expensive process in terms of time and

  13. Development of a Plastic Melt Waste Compactor for Space Missions Experiments and Prototype Design

    Science.gov (United States)

    Pace, Gregory; Wignarajah, Kanapathipillai; Pisharody, Suresh; Fisher, John

    2004-01-01

    This paper describes development at NASA Ames Research Center of a heat melt compactor that can be used on both near term and far term missions. Experiments have been performed to characterize the behavior of composite wastes that are representative of the types of wastes produced on current and previous space missions such as International Space Station, Space Shuttle, MIR and Skylab. Experiments were conducted to characterize the volume reduction, bonding, encapsulation and biological stability of the waste composite and also to investigate other key design issues such as plastic extrusion, noxious off-gassing and removal of the of the plastic waste product from the processor. The experiments provided the data needed to design a prototype plastic melt waste processor, a description of which is included in the paper.

  14. Microstructure, mechanical properties, and thermoelectric properties of hot-extruded p-type Te-doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Park, K; Seo, J; Lee, C

    1997-07-01

    The p-type Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds with Te dopant (4.0 and 6.0 wt%) and without dopant were fabricated by hot extrusion in the temperature range of 300 to 510 C under an extrusion ratio of 20:1. The undoped and Te doped compounds were highly dense and showed high crystalline quality. The grains contained many dislocations and were fine equiaxed ({approximately}1.0 {micro}m) owing to the dynamic recrystallization during the extrusion. The hot extrusion gave rise to the preferred orientation of grains. The bending strength and the figure of merit of the undoped and Te doped compounds were increased with increasing the extrusion temperature. The Te dopant significantly increased the figure of merit. The values of the figure of merit of the undoped and 4.0 wt% Te-doped compounds hot extruded at 440 C were 2.11 x 10{sup {minus}3}/K and 2.94 x 10{sup {minus}3}/K, respectively.

  15. Extrusion conditions affect chemical composition and in vitro digestion of select food ingredients.

    Science.gov (United States)

    Dust, Jolene M; Gajda, Angela M; Flickinger, Elizabeth A; Burkhalter, Toni M; Merchen, Neal R; Fahey, George C

    2004-05-19

    An experiment was conducted to determine the effects of extrusion conditions on chemical composition and in vitro hydrolytic and fermentative digestion of barley grits, cornmeal, oat bran, soybean flour, soybean hulls, and wheat bran. Extrusion conditions altered crude protein, fiber, and starch concentrations of ingredients. Organic matter disappearance (OMD) increased for extruded versus unprocessed samples of barley grits, cornmeal, and soybean flour that had been hydrolytically digested. After 8 h of fermentative digestion, OMD decreased as extrusion conditions intensified for barley grits and cornmeal but increased for oat bran, soybean hulls, and wheat bran. Total short-chain fatty acid production decreased as extrusion conditions intensified for barley grits, soybean hulls, and soybean flour. These data suggest that the effects of extrusion conditions on ingredient composition and digestion are influenced by the unique chemical characteristics of individual substrates.

  16. Quasi-superplasticity of a banded-grained Al-Mg-Y alloy processed by continuous casting-extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Furong, E-mail: cfr-lff@163.com [School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China); Zhu, Xiaotong [School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China); Huaian Dekema Semiconductor Co., Ltd., Huaian 223300 (China); Wang, Shuncheng [Institute of Materials Processing and Forming Technology, Guangdong General Research Institute of Industrial Technology, Guangzhou 510650 (China); Shi, Lu [School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China); Xu, Guangming [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Wen, Jinglin [School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China)

    2017-04-06

    The continuous casting-extrusion (CTE) process is a short-route technology for fabricating aluminum and aluminum alloy wires. A novel Al-1.44Mg-1.09Y alloy was prepared by CTE, and its mechanical properties and microstructure evolution were investigated at elevated temperatures to explore the hot tensile ductility of aluminum alloy wire. A true strain to failure of 1.159 was obtained at 773 K and 1.67×10{sup −2} s{sup −1}, and the present alloy exhibits high strain rate quasi-superplasticity. Microstructure observations reveal that it is difficult to realize the equiaxedness of elongated or textured grains through hot tensile deformation. A new deformation mechanism map (DMM) was constructed which predicts that dislocation climb at high stress dominates the high-temperature deformation process. This theoretical prediction using the DMM is in good agreement with experimental transmission-electron-microscopy results and with the estimated true stress exponent of 5 and the activation energy for deformation in the range 127.378―141.536 kJ mol{sup −1}. A new three-dimensional histogram containing a dynamic recovery (DRV) or dynamic recrystallization factor was constructed to demonstrate that the DRV mechanism dominates the deformation. Most experimental results are consistent with prediction using this histogram.

  17. Quasi-superplasticity of a banded-grained Al-Mg-Y alloy processed by continuous casting-extrusion

    International Nuclear Information System (INIS)

    Cao, Furong; Zhu, Xiaotong; Wang, Shuncheng; Shi, Lu; Xu, Guangming; Wen, Jinglin

    2017-01-01

    The continuous casting-extrusion (CTE) process is a short-route technology for fabricating aluminum and aluminum alloy wires. A novel Al-1.44Mg-1.09Y alloy was prepared by CTE, and its mechanical properties and microstructure evolution were investigated at elevated temperatures to explore the hot tensile ductility of aluminum alloy wire. A true strain to failure of 1.159 was obtained at 773 K and 1.67×10 −2 s −1 , and the present alloy exhibits high strain rate quasi-superplasticity. Microstructure observations reveal that it is difficult to realize the equiaxedness of elongated or textured grains through hot tensile deformation. A new deformation mechanism map (DMM) was constructed which predicts that dislocation climb at high stress dominates the high-temperature deformation process. This theoretical prediction using the DMM is in good agreement with experimental transmission-electron-microscopy results and with the estimated true stress exponent of 5 and the activation energy for deformation in the range 127.378―141.536 kJ mol −1 . A new three-dimensional histogram containing a dynamic recovery (DRV) or dynamic recrystallization factor was constructed to demonstrate that the DRV mechanism dominates the deformation. Most experimental results are consistent with prediction using this histogram.

  18. Continuous Preparation of 1:1 Haloperidol-Maleic Acid Salt by a Novel Solvent-Free Method Using a Twin Screw Melt Extruder.

    Science.gov (United States)

    Lee, Hung Lin; Vasoya, Jaydip M; Cirqueira, Marilia de Lima; Yeh, Kuan Lin; Lee, Tu; Serajuddin, Abu T M

    2017-04-03

    Salts are generally prepared by acid-base reaction in relatively large volumes of organic solvents, followed by crystallization. In this study, the potential for preparing a pharmaceutical salt between haloperidol and maleic acid by a novel solvent-free method using a twin-screw melt extruder was investigated. The pH-solubility relationship between haloperidol and maleic acid in aqueous medium was first determined, which demonstrated that 1:1 salt formation between them was feasible (pH max 4.8; salt solubility 4.7 mg/mL). Extrusion of a 1:1 mixture of haloperidol and maleic acid at the extruder barrel temperature of 60 °C resulted in the formation of a highly crystalline salt. The effects of operating temperature and screw configuration on salt formation were also investigated, and those two were identified as key processing parameters. Salts were also prepared by solution crystallization from ethyl acetate, liquid-assisted grinding, and heat-assisted grinding and compared with those obtained by melt extrusion by using DSC, PXRD, TGA, and optical microscopy. While similar salts were obtained by all methods, both melt extrusion and solution crystallization yielded highly crystalline materials with identical enthalpies of melting. During the pH-solubility study, a salt hydrate form was also identified, which, upon heating, converted to anhydrate similar to that obtained by other methods. There were previous reports of the formation of cocrystals, but not salts, by melt extrusion. 1 H NMR and single-crystal X-ray diffraction confirmed that a salt was indeed formed in the present study. The haloperidol-maleic acid salt obtained was nonhygroscopic in the moisture sorption study and converted to the hydrate form only upon mixing with water. Thus, we are reporting for the first time a relatively simple and solvent-free twin-screw melt extrusion method for the preparation of a pharmaceutical salt that provides material comparable to that obtained by solution

  19. A hybrid twin screw extrusion/electrospinning method to process nanoparticle-incorporated electrospun nanofibres

    International Nuclear Information System (INIS)

    Erisken, Cevat; Kalyon, Dilhan M; Wang Hongjun

    2008-01-01

    A new hybrid methodology that fully integrates the processing capabilities of the twin screw extrusion process (conveying solids, melting, dispersive and distributive mixing, pressurization, temperature profiling, devolatilization) with electrospinning is described. The hybrid process is especially suited to the dispersion of nanoparticles into polymeric binders and the generation of nanoparticle-incorporated fibres and nanofibres. The new technology base is demonstrated with the dispersion of β-tricalcium phosphate (β-TCP) nanoparticles into poly(ε-caprolactone) (PCL) to generate biodegradable non-woven meshes that can be targeted as scaffolds for tissue engineering applications. The new hybrid method yielded fibre diameters in the range of 200-2000 nm for both PCL and β-TCP/PCL (35% by weight) composite scaffolds. The degree of crystallinity of polycaprolactone meshes could be manipulated in the 35.1-41% range, using the voltage strength as a parameter. The electrospinning process, integrated with dispersive kneading disc elements, facilitated the decrease of the cluster sizes and allowed the continuous compounding of the nanoparticles into the biodegradable polymer prior to electrospinning. Thermogravimetric analysis (TGA) of the non-woven meshes validated the continuous incorporation of 35 ± 1.5% (by weight) β-TCP nanoparticles for a targeted concentration of 35%. Uniaxial tensile testing of the meshes with and without the nanoparticles indicated that the ultimate tensile strength at break of the meshes increased from 0.47 ± 0.04 to 0.79 ± 0.08 MPa upon the incorporation of the β-TCP nanoparticles. This demonstration study suggests that the new technology base is particularly suitable for the concomitant dispersion and electrospinning of nanoparticles in the generation of myriad types of functional nanofibres

  20. Hot Deformation Behavior and Processing Maps of Diamond/Cu Composites

    Science.gov (United States)

    Zhang, Hongdi; Liu, Yue; Zhang, Fan; Zhang, Di; Zhu, Hanxing; Fan, Tongxiang

    2018-06-01

    The hot deformation behaviors of 50 vol pct uncoated and Cr-coated diamond/Cu composites were investigated using hot isothermal compression tests under the temperature and strain rate ranging from 1073 K to 1273 K (800 °C to 1000 °C) and from 0.001 to 5 s-1, respectively. Dynamic recrystallization was determined to be the primary restoration mechanism during deformation. The Cr3C2 coating enhanced the interfacial bonding and resulted in a larger flow stress for the Cr-coated diamond/Cu composites. Moreover, the enhanced interfacial affinity led to a higher activation energy for the Cr-coated diamond/Cu composites (238 kJ/mol) than for their uncoated counterparts (205 kJ/mol). The strain-rate-dependent constitutive equations of the diamond/Cu composites were derived based on the Arrhenius model, and a high correlation ( R = 0.99) was observed between the calculated flow stresses and experimental data. With the help of processing maps, hot extrusions were realized at 1123 K/0.01 s-1 and 1153 K/0.01 s-1 (850 °C/0.01 s-1 and 880 °C/0.01 s-1) for the uncoated and coated diamond/Cu composites, respectively. The combination of interface optimization and hot extrusion led to increases of the density and thermal conductivity, thereby providing a promising route for the fabrication of diamond/Cu composites.

  1. Extrusão de misturas de castanha do Brasil com mandioca Extrusion of Brazil nut and cassava flour mixtures

    Directory of Open Access Journals (Sweden)

    Maria Luzenira de Souza

    2008-06-01

    Full Text Available Considerando-se que a castanha do Brasil apresenta elevado potencial nutritivo, baixo consumo no Brasil, baixo valor agregado e é um produto orgânico, além da alta produtividade, do baixo custo da mandioca e da tecnologia de extrusão termoplástica apresentarem ampla aplicabilidade e vantagens, este trabalho teve como objetivo empregar estas três variáveis, para formular misturas com castanha do Brasil e farinha de mandioca e processá-las por extrusão, visando à obtenção de produtos extrusados ricos em proteína vegetal e prontos para o consumo. Foram utilizadas torta de amêndoa de castanha do Brasil semidesengordurada e farinha de mandioca para formulações das misturas para extrusão. Aplicou-se o delineamento fatorial completo composto central (2³, com 3 variáveis independentes e a metodologia de superfície de resposta foi usada para avaliar os resultados da composição centesimal e o valor calórico, frente às variações de castanha, umidade e temperatura. Os resultados indicam que as formulações com maiores quantidades de castanha apresentam quantidades de proteínas, lipídios e cinzas mais elevadas, já as formulações com menores teores de castanha apresentam maiores percentuais de carboidratos. Os coeficientes de regressão médios do modelo estatístico para as respostas são: umidade 7,40; carboidratos 51,09; proteínas 15,34; lipídios 11,77; fibra total 9,92 e kcal 371,65. Os ensaios com menores teores de castanha e maiores de farinha apresentam-se mais expandidos e de cor clara, enquanto que aqueles com maiores teores de castanha não se expandem e têm a cor acinzentada. Conclui-se que a adição de castanha semidesengordurada à farinha de mandioca pode ser submetida à extrusão, originando um produto extrusado fonte de proteína vegetal, pronto para o consumo e que pode atender à exigência de consumidores que não utilizam proteínas de origem animal.Considering that Brazil nut presents high nutritional

  2. 77 FR 74466 - Aluminum Extrusions From the People's Republic of China: Notice of Court Decision Not in Harmony...

    Science.gov (United States)

    2012-12-14

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-570-968] Aluminum Extrusions From the... countervailing duty (CVD) investigation of aluminum extrusions from the People's Republic of China (PRC) \\1... Aluminum Extrusions From the People's Republic of China: Final Affirmative Countervailing Duty...

  3. Application of the zone-melting technique to metal chelate systems-VI A new apparatus for zone-melting chromatography.

    Science.gov (United States)

    Maeda, S; Kobayashi, H; Ueno, K

    1973-07-01

    An improved apparatus has been constructed for zone-melting chromatography. An essential feature of the apparatus is that the length of the molten zone can be kept constant during a zone-melting operation, by employing heating and cooling compartments which are separated from each other by double partition plates. Each compartment is heated or cooled with jets of hot or cold air. The apparatus is suitable for organic materials melting in the range between 40 degrees and 180 degrees . The distribution of metal ion along the column after zone melting of copper acetylacetonate in 2-methoxynaphthalene was a smooth curve. The plot of the position of maximum concentration, x(max), against the number of zone passes, n, gave a relationship in accordance with theoretical prediction.

  4. DEPENDENCY OF SULFATE SOLUBILITY ON MELT COMPOSITION AND MELT POLYMERIZATION

    International Nuclear Information System (INIS)

    JANTZEN, CAROL M.

    2004-01-01

    Sulfate and sulfate salts are not very soluble in borosilicate waste glass. When sulfate is present in excess it can form water soluble secondary phases and/or a molten salt layer (gall) on the melt pool surface which is purported to cause steam explosions in slurry fed melters. Therefore, sulfate can impact glass durability while formation of a molten salt layer on the melt pool can impact processing. Sulfate solubility has been shown to be compositionally dependent in various studies, (e.g. , B2O3, Li2O, CaO, MgO, Na2O, and Fe2O3 were shown to increase sulfate solubility while Al2O3 and SiO2 decreased sulfate solubility). This compositional dependency is shown to be related to the calculated melt viscosity at various temperatures and hence the melt polymerization

  5. Plasma arc melting of zirconium

    International Nuclear Information System (INIS)

    Tubesing, P.K.; Korzekwa, D.R.; Dunn, P.S.

    1997-01-01

    Zirconium, like some other refractory metals, has an undesirable sensitivity to interstitials such as oxygen. Traditionally, zirconium is processed by electron beam melting to maintain minimum interstitial contamination. Electron beam melted zirconium, however, does not respond positively to mechanical processing due to its large grain size. The authors undertook a study to determine if plasma arc melting (PAM) technology could be utilized to maintain low interstitial concentrations and improve the response of zirconium to subsequent mechanical processing. The PAM process enabled them to control and maintain low interstitial levels of oxygen and carbon, produce a more favorable grain structure, and with supplementary off-gassing, improve the response to mechanical forming

  6. Genetic Architecture of Anther Extrusion in Spring and Winter Wheat

    Directory of Open Access Journals (Sweden)

    Quddoos H. Muqaddasi

    2017-05-01

    Full Text Available Hybrid wheat breeding is gaining prominence worldwide because it ensures higher and more static yield than conventionally bred varieties. The cleistogamous floral architecture of wheat (Triticum aestivum L. impedes anthers inside the floret, making it largely an inbreeder. For hybrid seed production, high anther extrusion is needed to promote cross pollination and to ensure a high level of pollen availability for the seed plant. This study, therefore, aimed at the genetic dissection of anther extrusion (AE in panels of spring (SP, and winter wheat (WP accessions by genome wide association studies (GWAS. We performed GWAS to identify the SNP markers potentially linked with AE in each panel separately. Phenotypic data were collected for 3 years for each panel. The average levels of Pearson's correlation (r among all years and their best linear unbiased estimates (BLUEs within both panels were high (r(SP = 0.75, P < 0.0001;r(WP = 0.72, P < 0.0001. Genotypic data (with minimum of 0.05 minor allele frequency applied included 12,066 and 12,191 SNP markers for SP and WP, respectively. Both genotypes and environment influenced the magnitude of AE. In total, 23 significant (|log10(P| > 3.0 marker trait associations (MTAs were detected (SP = 11; WP = 12. Anther extrusion behaved as a complex trait with significant markers having either favorable or unfavorable additive effects and imparting minor to moderate levels of phenotypic variance (R2(SP = 9.75−14.24%; R2 (WP = 9.44−16.98%. All mapped significant markers as well as the markers within their significant linkage disequilibrium (r2 ≥ 0.30 regions were blasted against wheat genome assembly (IWGSC1+popseq to find the corresponding genes and their high confidence descriptions were retrieved. These genes and their orthologs in Hordeum vulgare, Brachypodium distachyon, Oryza sativa, and Sorghum bicolor revealed syntenic genomic regions potentially involved in flowering-related traits. Moreover, the

  7. Frictional melting and stick-slip behavior in volcanic conduits

    Science.gov (United States)

    Kendrick, Jackie Evan; Lavallee, Yan; Hirose, Takehiro; di Toro, Giulio; Hornby, Adrian Jakob; Hess, Kai-Uwe; Dingwell, Donald Bruce

    2013-04-01

    Dome-building eruptions have catastrophic potential, with dome collapse leading to devastating pyroclastic flows with almost no precursory warning. During dome growth, the driving forces of the buoyant magma may be superseded by controls along conduit margins; where brittle fracture and sliding can lead to formation of lubricating cataclasite and gouge. Under extreme friction, pseudotachylyte may form at the conduit margin. Understanding the conduit margin processes is vital to understanding the continuation of an eruption and we postulate that pseudotachylyte generation could be the underlying cause of stick-slip motion and associated seismic "drumbeats", which are so commonly observed at dome-building volcanoes. This view is supported by field evidence in the form of pseudotachylytes identified in lava dome products at Soufrière Hills (Montserrat) and Mount St. Helens (USA). Both eruptions were characterised by repetitive, periodic seismicity and lava spine extrusion of highly viscous magma. High velocity rotary shear (HVR) experiments demonstrate the propensity for melting of the andesitic and dacitic material (from Soufrière Hills and Mount St. Helens respectively) at upper conduit stress conditions (HVR experiments which mimic rapid velocity fluctuations in stick-slip behavior demonstrate velocity-weakening behavior of melt, with a tendency for unstable slip. During ascent, magma may slip and undergo melting along the conduit margin. In the process the shear resistance of the slip zone is increased, acting as a viscous brake halting slip (the "stick" of stick-slip motion). Sufficient buoyancy-driven pressures from ascending magma below eventually overcome resistance to produce a rapid slip event (the "slip") along the melt-bearing slip zone, which is temporarily lubricated due to velocity-weakening. New magma below experiences the same slip event more slowly (as the magma decompresses) to produce a viscous brake and the process is repeated. This allows a

  8. Some physicochemical properties of dextrin produced by extrusion process

    Directory of Open Access Journals (Sweden)

    Achmat Sarifudin

    2014-06-01

    Full Text Available Dextrinization of corn starch by twin screw extruder was studied. The effect of extruder operating conditions (five different screw speeds: 35, 45, 55, 65, and 70; and three temperatures: 125, 130, and 135 °C on some physicochemical properties of dextrin (total soluble solid, water absorption index, water solubility index, and total color difference was investigated. Results showed that as the screw speed and temperature of extrusion were increased the water absorption index of dextrin tended to drop meanwhile the total soluble solid, water solubility index, and color were inclined to rise. The range of total soluble solid, water absorption index, water solubility index and total color difference was 2.1–4.6 Brix, 159–203%, 20–51%, 3.5–14.1, respectively.

  9. Study on extrusion process of SiC ceramic matrix

    Science.gov (United States)

    Dai, Xiao-Yuan; Shen, Fan; Ji, Jia-You; Wang, Shu-Ling; Xu, Man

    2017-11-01

    In this thesis, the extrusion process of SiC ceramic matrix has been systematically studied.The effect of different cellulose content on the flexural strength and pore size distribution of SiC matrix was discussed.Reselts show that with the increase of cellulose content, the flexural strength decreased.The pore size distribution in the sample was 1um-4um, and the 1um-2um concentration was more concentrated. It is found that the cellulose content has little effect on the pore size distribution.When the cellulose content is 7%, the flexural strength of the sample is 40.9Mpa. At this time, the mechanical properties of the sample are the strongest.

  10. Binder extrusion of sliding wear of WC-Co alloys

    International Nuclear Information System (INIS)

    Larsen-Basse, J.

    1985-01-01

    It has previously been proposed that preferential removal of the cobalt binder is an important mechanism in the abrasive wear of cemented carbides in the WC-Co family. It is here demonstrated that binder extrusion occurs also in metal-to-metal sliding wear contacts. The wear scar generated by sliding a hardened steel ball repeatedly over a polished WC-Co surface was studied by SEM. The extruded cobalt fragments accumulate by surface defects, such as cracks caused by the sliding loaded ball, and gradual microfragmentation of the carbide grains follows. The energy required to extrude the cobalt and cause the gradual change in surface layer microstructure is provided by the frictional forces

  11. Characterization of extrusion flow using particle image velocimetry

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available The aim of this study was the characterization of polymer flows within an extrusion die using particle image velocimetry (PIV in very constraining conditions (high temperature, pressure and velocity. Measurements were realized on semi-industrial equipments in order to have test conditions close to the industrial ones. Simple flows as well as disrupted ones were studied in order to determine the capabilities and the limits of the method. The analysis of the velocity profiles pointed out significant wall slip, which was confirmed by rheological measurements based on Mooney's method. Numerical simulations were used to connect the two sets of measurements and to simulate complex velocity profiles for comparison to the experimental ones. A good agreement was found between simulations and experiments providing wall slip is taken into account in the simulation.

  12. Fatigue Behaviors of Materials Processed by Planar Twist Extrusion

    Science.gov (United States)

    Ebrahimi, Mahmoud

    2017-12-01

    Since the last decade, the fabrication of ultrafine grain and nanostructure metals and alloys has attracted much attention in the field of materials engineering. The present study aimed at experimentally investigating the fatigue properties that are of great importance in dynamic structures before and after the planar twist extrusion process for both commercially pure copper and 6061 aluminum alloy. The results indicated that the yield strength, tensile strength, hardness, and fatigue endurance of copper increased by about 398, 122, 198, and 183 pct, respectively, while they improved by about 429, 212, 227, and 148 pct, respectively, in aluminum alloy as compared to the initial conditions. The stress-strain curves displayed sizable reduction of strain hardening. Furthermore, grain-size correction factors based on the empirical results were introduced to include the effect of the grain-size effect on both low and high-cycle fatigue strengths of the material.

  13. Nitrogen Control in VIM Melts

    Science.gov (United States)

    Jablonski, P. D.; Hawk, J. A.

    NETL has developed a design and control philosophy for the addition of nitrogen to austenitic and ferritic steels. The design approach uses CALPHAD as the centerpiece to predict the level to which nitrogen is soluble in both the melt and the solid. Applications of this technique have revealed regions of "exclusion" in which the alloy, while within specification limits of prescribed, cannot be made by conventional melt processing. Furthermore, other investigations have found that substantial retrograde solubility of nitrogen exists, which can become problematic during subsequent melt processing and/or other finishing operations such as welding. Additionally, the CALPHAD method has been used to adjust primary melt conditions. To that end, nitrogen additions have been made using chrome nitride, silicon nitride, high-nitrogen ferrochrome as well as nitrogen gas. The advantages and disadvantages of each approach will be discussed and NETL experience in this area will be summarized with respect to steel structure.

  14. Theoretical melting curve of caesium

    International Nuclear Information System (INIS)

    Simozar, S.; Girifalco, L.A.; Pennsylvania Univ., Philadelphia

    1983-01-01

    A statistical-mechanical model is developed to account for the complex melting curve of caesium. The model assumes the existence of three different species of caesium defined by three different electronic states. On the basis of this model, the free energy of melting and the melting curve are computed up to 60 kbar, using the solid-state data and the initial slope of the fusion curve as input parameters. The calculated phase diagram agrees with experiment to within the experimental error. Other thermodynamic properties including the entropy and volume of melting were also computed, and they agree with experiment. Since the theory requires only one adjustable constant, this is taken as strong evidence that the three-species model is satisfactory for caesium. (author)

  15. Melting curves of gammairradiated DNA

    International Nuclear Information System (INIS)

    Hofer, H.; Altmann, H.; Kehrer, M.

    1978-08-01

    Melting curves of gammairradiated DNA and data derived of them, are reported. The diminished stability is explained by basedestruction. DNA denatures completely at room temperature, if at least every fifth basepair is broken or weakened by irradiation. (author)

  16. Pressure melting and ice skating

    Science.gov (United States)

    Colbeck, S. C.

    1995-10-01

    Pressure melting cannot be responsible for the low friction of ice. The pressure needed to reach the melting temperature is above the compressive failure stress and, if it did occur, high squeeze losses would result in very thin films. Pure liquid water cannot coexist with ice much below -20 °C at any pressure and friction does not increase suddenly in that range. If frictional heating and pressure melting contribute equally, the length of the wetted contact could not exceed 15 μm at a speed of 5 m/s, which seems much too short. If pressure melting is the dominant process, the water films are less than 0.08 μm thick because of the high pressures.

  17. Extrusion of the uranium-0.75 weight percent titanium alloy

    International Nuclear Information System (INIS)

    Jackson, R.J.; Lundberg, M.R.; Boland, J.F.

    1975-01-01

    Procedures are described for extruding the U--0.75 wt percent Ti alloy in the high alpha region (600 to 640 0 C) , and in the upper gamma region (900 to 1000 0 C). The casting of sound extrusion billets has importance in the production of sound extrusions, and procedures are given for casting sound billets up to 1,100 kilograms . Also important in producing sound extrusions is the use of glass lubricants. Reduction ratios of greater than 50 to 1 were achieved on reasonably sized billets. Extrusion constants of 48,000 pounds per square inch (psi) [296 megapascals (MPa)] for alpha phase (630 0 C) and 8,000 psi (56 MPa) for gamma phase (950 0 C) were achieved. Gamma-phase extrusion has preference over alpha-phase extrusion in that larger billets can be used and temperature control is not as critical. However alpha-phase extrusion offers better surface finish, less die wear, and fewer oxidation problems. Billets up to 14 inches in diameter have been successfully gamma-extruded and plans exist for extruding billets up to 20 inches (508 millimetres) in diameter. (U.S.)

  18. Hot Weather Tips

    Science.gov (United States)

    ... the person plenty of water and fruit or vegetable juice even if they say they’re not thirsty. No alcohol, coffee or tea. Seek medical help if you suspect dehydration. Light meals: Avoid hot, heavy meals and don’ ...

  19. China's 'Hot Money' Problems

    National Research Council Canada - National Science Library

    Martin, Michael F; Morrison, Wayne M

    2008-01-01

    .... The recent large inflow of financial capital into China, commonly referred to as "hot money," has led some economists to warn that such flows may have a destabilizing effect on China's economy...

  20. Deep Crustal Melting and the Survival of Continental Crust

    Science.gov (United States)

    Whitney, D.; Teyssier, C. P.; Rey, P. F.; Korchinski, M.

    2017-12-01

    Plate convergence involving continental lithosphere leads to crustal melting, which ultimately stabilizes the crust because it drives rapid upward flow of hot deep crust, followed by rapid cooling at shallow levels. Collision drives partial melting during crustal thickening (at 40-75 km) and/or continental subduction (at 75-100 km). These depths are not typically exceeded by crustal rocks that are exhumed in each setting because partial melting significantly decreases viscosity, facilitating upward flow of deep crust. Results from numerical models and nature indicate that deep crust moves laterally and then vertically, crystallizing at depths as shallow as 2 km. Deep crust flows en masse, without significant segregation of melt into magmatic bodies, over 10s of kms of vertical transport. This is a major mechanism by which deep crust is exhumed and is therefore a significant process of heat and mass transfer in continental evolution. The result of vertical flow of deep, partially molten crust is a migmatite dome. When lithosphere is under extension or transtension, the deep crust is solicited by faulting of the brittle upper crust, and the flow of deep crust in migmatite domes traverses nearly the entire thickness of orogenic crust in Recognition of the importance of migmatite (gneiss) domes as archives of orogenic deep crust is applicable to determining the chemical and physical properties of continental crust, as well as mechanisms and timescales of crustal differentiation.

  1. Melting in super-earths.

    Science.gov (United States)

    Stixrude, Lars

    2014-04-28

    We examine the possible extent of melting in rock-iron super-earths, focusing on those in the habitable zone. We consider the energetics of accretion and core formation, the timescale of cooling and its dependence on viscosity and partial melting, thermal regulation via the temperature dependence of viscosity, and the melting curves of rock and iron components at the ultra-high pressures characteristic of super-earths. We find that the efficiency of kinetic energy deposition during accretion increases with planetary mass; considering the likely role of giant impacts and core formation, we find that super-earths probably complete their accretionary phase in an entirely molten state. Considerations of thermal regulation lead us to propose model temperature profiles of super-earths that are controlled by silicate melting. We estimate melting curves of iron and rock components up to the extreme pressures characteristic of super-earth interiors based on existing experimental and ab initio results and scaling laws. We construct super-earth thermal models by solving the equations of mass conservation and hydrostatic equilibrium, together with equations of state of rock and iron components. We set the potential temperature at the core-mantle boundary and at the surface to the local silicate melting temperature. We find that ancient (∼4 Gyr) super-earths may be partially molten at the top and bottom of their mantles, and that mantle convection is sufficiently vigorous to sustain dynamo action over the whole range of super-earth masses.

  2. Investigation of the process energy demand in polymer extrusion: A brief review and an experimental study

    International Nuclear Information System (INIS)

    Abeykoon, Chamil; Kelly, Adrian L.; Brown, Elaine C.; Vera-Sorroche, Javier; Coates, Phil D.; Harkin-Jones, Eileen; Howell, Ken B.; Deng, Jing; Li, Kang; Price, Mark

    2014-01-01

    Highlights: • Energy consumption and losses in polymer extrusion are discussed. • This compares energy consumption in polymer extrusion at different conditions. • The role of power factor on energy efficiency in polymer extrusion is explored. • Empirical models on extruder energy consumption are provided. • Computer modelling of energy consumption of polymer extrusion is performed. - Abstract: Extrusion is one of the fundamental production methods in the polymer processing industry and is used in the production of a large number of commodities in a diverse industrial sector. Being an energy intensive production method, process energy efficiency is one of the major concerns and the selection of the most energy efficient processing conditions is a key to reducing operating costs. Usually, extruders consume energy through the drive motor, barrel heaters, cooling fans, cooling water pumps, gear pumps, etc. Typically the drive motor is the largest energy consuming device in an extruder while barrel/die heaters are responsible for the second largest energy demand. This study is focused on investigating the total energy demand of an extrusion plant under various processing conditions while identifying ways to optimise the energy efficiency. Initially, a review was carried out on the monitoring and modelling of the energy consumption in polymer extrusion. Also, the power factor, energy demand and losses of a typical extrusion plant were discussed in detail. The mass throughput, total energy consumption and power factor of an extruder were experimentally observed over different processing conditions and the total extruder energy demand was modelled empirically and also using a commercially available extrusion simulation software. The experimental results show that extruder energy demand is heavily coupled between the machine, material and process parameters. The total power predicted by the simulation software exhibits a lagging offset compared with the

  3. Glacial melting in Himalaya

    Directory of Open Access Journals (Sweden)

    Kavita Tariyal

    2013-07-01

    Full Text Available Mountains are amongst the most flimsy environments on Earth. They are prosperous repositories of biodiversity, water and providers of ecosystem goods and services on which downstream communities, both regional and global, rely. The transport of atmospheric pollutants and climate-altering substances can significantly impact high mountain areas, which are generally considered “clean” regions. The snow glaciers of the Himalayas, considered the “third pole”, one of the largest stores of water on the planet and accelerated melting could have far-reaching effects, such as flooding in the short-term and water shortages in the long-term as the glaciers shrink. The data available on temperature in Himalayas indicate that warming during last 3-4 decades has been more than the global average over the last century. Some of the values indicate that the Himalayas are warming 5-6 times more than the global average. Mountain systems are seen globally as the prime sufferers from climate change. There is a severe gap in the knowledge of the short and long-term implications of the impact of climate change on water and hazards in the Himalayas, and their downstream river basins. Most studies have excluded the Himalayan region because of its extreme and complex topography and the lack of adequate rain gauge data. There is an urgent need to close the knowledge gap by establishing monitoring schemes for snow, ice and water; downscaling climate models; applying hydrological models to predict water availability; and developing basin wide scenarios, which also take water demand and socioeconomic development into account. Climate change induced hazards such as floods, landslides and droughts will impose considerable stresses on the livelihoods of mountain people and downstream populations. Enhancing resilience and promoting adaptation in mountain areas have thus become among the most important priorities of this decade. It is important to strengthen local

  4. Iron single crystal growth from a lithium-rich melt

    Science.gov (United States)

    Fix, M.; Schumann, H.; Jantz, S. G.; Breitner, F. A.; Leineweber, A.; Jesche, A.

    2018-03-01

    α -Fe single crystals of rhombic dodecahedral habit were grown from a Li84N12Fe∼3 melt. Crystals of several millimeter along a side form at temperatures around T ≈ 800 ° C. Upon further cooling the growth competes with the formation of Fe-doped Li3N. The b.c.c. structure and good sample quality of α -Fe single crystals were confirmed by X-ray and electron diffraction as well as magnetization measurements and chemical analysis. A nitrogen concentration of 90 ppm was detected by means of carrier gas hot extraction. Scanning electron microscopy did not reveal any sign of iron nitride precipitates.

  5. Methods for Melting Temperature Calculation

    Science.gov (United States)

    Hong, Qi-Jun

    Melting temperature calculation has important applications in the theoretical study of phase diagrams and computational materials screenings. In this thesis, we present two new methods, i.e., the improved Widom's particle insertion method and the small-cell coexistence method, which we developed in order to capture melting temperatures both accurately and quickly. We propose a scheme that drastically improves the efficiency of Widom's particle insertion method by efficiently sampling cavities while calculating the integrals providing the chemical potentials of a physical system. This idea enables us to calculate chemical potentials of liquids directly from first-principles without the help of any reference system, which is necessary in the commonly used thermodynamic integration method. As an example, we apply our scheme, combined with the density functional formalism, to the calculation of the chemical potential of liquid copper. The calculated chemical potential is further used to locate the melting temperature. The calculated results closely agree with experiments. We propose the small-cell coexistence method based on the statistical analysis of small-size coexistence MD simulations. It eliminates the risk of a metastable superheated solid in the fast-heating method, while also significantly reducing the computer cost relative to the traditional large-scale coexistence method. Using empirical potentials, we validate the method and systematically study the finite-size effect on the calculated melting points. The method converges to the exact result in the limit of a large system size. An accuracy within 100 K in melting temperature is usually achieved when the simulation contains more than 100 atoms. DFT examples of Tantalum, high-pressure Sodium, and ionic material NaCl are shown to demonstrate the accuracy and flexibility of the method in its practical applications. The method serves as a promising approach for large-scale automated material screening in which

  6. Extrusion and drawing of zircaloy 2. Production of pressure tubes for EL-4; Filage et etirage du zircaloy 2. Realisation des tubes de force pour EL-4

    Energy Technology Data Exchange (ETDEWEB)

    Thevenet, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Buffet, J [Cefilac (France)

    1964-07-01

    The authors give briefly the physical mechanical and chemical properties of zircaloy 2, as far as the transformation of this alloy is concerned. Extrusion: After a few general remarks concerning the extrusion and co-extrusion, including a comparison of the deformation resistance of canning metals and of zircaloy 2, the following points are considered: - the difficulties occurring because of the use of this alloy: - atmosphere protection - adjustment on to the machine tools - low thermal conductivity - economy of the metal (price) - the factors affecting the quality of the extruded products extrusion under a copper can and under lubricant glass - fine grain structure - temperature homogeneity - working temperature The transformation cycle - '550 kg ingot - preliminary shape 'for drawing of EL-4 tubes (112 x 120 L 12 m)' - is described in detail (extrusion or forging of the {phi} = 340 ingot into {phi} = 220 billets, cutting into lengths and hot drilling at {phi} = 125, fixing into a copper can and rough extrusion). Drawing: The main difficulties are due to seizing of the tools and to the necessity of protecting the alloy from the atmosphere during annealings. A brief description is given of drawing out on a short mandrel, on a long mandrel, of laminating on a reducing machine and of the carrying out of an annealing, as well as of the production of EL-4 tubes ({phi} =107 x 113 L 430 m) by drawing out shapes having a size of 112 x 120 on long mandrels. Conclusion: It is possible by extrusion and drawing to produce zircaloy 2 tubes similar to those which may be obtained normally using stainless steel. (authors) [French] Les auteurs donnent un resume succint des proprietes physiques mecaniques et chimiques du zircaloy 2 en ce qui concerne la transformation de cet alliage. Filage: Apres quelques generalites sur le filage et le cofilage, dont une comparaison entre les resistances a la deformation des metaux de gainage et du zircaloy 2, on etudie successivement: - les

  7. Energy flux of hot atoms

    International Nuclear Information System (INIS)

    Wotzak, G.P.; Kostin, M.D.

    1976-01-01

    The process in which hot atoms collide with thermal atoms of a gas, transfer kinetic energy to them, and produce additional hot atoms is investigated. A stochastic method is used to obtain numerical results for the spatial and time dependent energy flux of hot atoms in a gas. The results indicate that in hot atom systems a front followed by an intense energy flux of hot atoms may develop

  8. Online shear viscosity measurement of starchy melts enriched in wheat bran.

    Science.gov (United States)

    Robin, Frédéric; Bovet, Nicolas; Pineau, Nicolas; Schuchmann, Heike P; Palzer, Stefan

    2011-01-01

    Addition of wheat bran to flours modifies their expansion properties after cooking extrusion. This can be attributed to changes in the melt shear viscosity at the die. The effect of wheat bran concentration added to achieve 2 levels of dietary fibers of 12. 6% and 24.4%, and process conditions on the shear viscosity of wheat flour was therefore assessed using an online twin-slit rheometer. The shear viscosity measured at 30 s⁻¹ ranged from 9.5 × 10³ to 53.4 × 10³ Pa s. Regardless of the process conditions and bran concentration, the extruded melts showed a pseudoplastic behavior with a power law index n ranging from 0.05 to 0.27. Increasing the barrel temperature of the extruder from 120 to 180 °C, the water content from 18% to 22% or the screw speed from 400 to 800 rpm significantly decreased the melt shear viscosity at the extruder exit. The addition of bran significantly increased the melt shear viscosity only at the highest bran concentration. The effect was process condition dependant. Mathematical interpretations, based upon observations, of the experimental data were carried out. They can be used to predict the effect of the process conditions on the melt shear viscosity at the die of extruded wheat flour with increasing bran concentration. The viscosity data will be applied in future works to study the expansion properties of extruded wheat flour supplemented with bran. Incorporation of wheat bran, a readily available and low cost by-product, in extruded puffed foods is constrained due to its negative effect on the product texture. Understanding the effect of wheat bran on rheological properties of extruded melts, driving the final product properties, is essential to provide solutions to the food industry and enhance its use. © 2011 Institute of Food Technologists®

  9. Melting of superheated molecular crystals

    Science.gov (United States)

    Cubeta, Ulyana; Bhattacharya, Deepanjan; Sadtchenko, Vlad

    2017-07-01

    Melting dynamics of micrometer scale, polycrystalline samples of isobutane, dimethyl ether, methyl benzene, and 2-propanol were investigated by fast scanning calorimetry. When films are superheated with rates in excess of 105 K s-1, the melting process follows zero-order, Arrhenius-like kinetics until approximately half of the sample has transformed. Such kinetics strongly imply that melting progresses into the bulk via a rapidly moving solid-liquid interface that is likely to originate at the sample's surface. Remarkably, the apparent activation energies for the phase transformation are large; all exceed the enthalpy of vaporization of each compound and some exceed it by an order of magnitude. In fact, we find that the crystalline melting kinetics are comparable to the kinetics of dielectric α-relaxation in deeply supercooled liquids. Based on these observations, we conclude that the rate of non-isothermal melting for superheated, low-molecular-weight crystals is limited by constituent diffusion into an abnormally dense, glass-like, non-crystalline phase.

  10. Improved capacitive melting curve measurements

    International Nuclear Information System (INIS)

    Sebedash, Alexander; Tuoriniemi, Juha; Pentti, Elias; Salmela, Anssi

    2009-01-01

    Sensitivity of the capacitive method for determining the melting pressure of helium can be enhanced by loading the empty side of the capacitor with helium at a pressure nearly equal to that desired to be measured and by using a relatively thin and flexible membrane in between. This way one can achieve a nanobar resolution at the level of 30 bar, which is two orders of magnitude better than that of the best gauges with vacuum reference. This extends the applicability of melting curve thermometry to lower temperatures and would allow detecting tiny anomalies in the melting pressure, which must be associated with any phenomena contributing to the entropy of the liquid or solid phases. We demonstrated this principle in measurements of the crystallization pressure of isotopic helium mixtures at millikelvin temperatures by using partly solid pure 4 He as the reference substance providing the best possible universal reference pressure. The achieved sensitivity was good enough for melting curve thermometry on mixtures down to 100 μK. Similar system can be used on pure isotopes by virtue of a blocked capillary giving a stable reference condition with liquid slightly below the melting pressure in the reference volume. This was tested with pure 4 He at temperatures 0.08-0.3 K. To avoid spurious heating effects, one must carefully choose and arrange any dielectric materials close to the active capacitor. We observed some 100 pW loading at moderate excitation voltages.

  11. Automatic Control of Silicon Melt Level

    Science.gov (United States)

    Duncan, C. S.; Stickel, W. B.

    1982-01-01

    A new circuit, when combined with melt-replenishment system and melt level sensor, offers continuous closed-loop automatic control of melt-level during web growth. Installed on silicon-web furnace, circuit controls melt-level to within 0.1 mm for as long as 8 hours. Circuit affords greater area growth rate and higher web quality, automatic melt-level control also allows semiautomatic growth of web over long periods which can greatly reduce costs.

  12. effectof extrusion conditions on aflatoxin content of corn–peanut flakes

    African Journals Online (AJOL)

    Aynadis

    metabolites which can be observed on food stuffs or ... Extrusion cooking technologies are used to ..... effective interaction to reduce aflatoxin B1in the ..... Drug. Administration, “Guidance for industry: Action levels for poisonous or deleterious.

  13. 76 FR 323 - Aluminum Extrusions From the People's Republic of China: Notice of Amended Preliminary...

    Science.gov (United States)

    2011-01-04

    ... finished good. The scope also excludes aluminum alloy sheet or plates produced by other than the extrusion... calculation program by coding the decimal point in the wrong place. The Department agrees, and finds that this...

  14. AFSC/RACE/SAP/Swiney: Primiparous and multiparous Tanner crab egg extrusion, embryo development and hatching

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study compares timing of egg extrusion, embryo development, timing and duration of eclosion, and incubation periods of Kodiak, Alaska primiparous and...

  15. Effect of rapid cooling and extrusion ratio on the mechanical property of Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taek-Soo, E-mail: tskim@kitech.re.k [Center for Echo Materials and Processing, Korea Institute of Industrial Technology, 7-47 Techno-park Songdo, Incheon 406-130 (Korea, Republic of)

    2010-08-15

    Mg{sub 95}Zn{sub 4.3}Y{sub 0.7} (at.%) alloy powders were prepared using an inert gas atomizer, followed by warm extrusion. The powders were almost spherical in shape, and the grain size, compared with the cast product, was fine being less than 5 {mu}m. The microstructure of bars extruded was examined as a function of the extrusion ratio using scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS) and X-ray diffractometer (XRD). As the extrusion ratio increased from 10:1 to 20:1, the powders fully deformed with refining the grain size. Both the ultimate strength and elongation also showed a dependence on the extrusion ratio.

  16. Current deformation rates and extrusion of the northwestern Okhotsk plate, northeast Russia

    Science.gov (United States)

    Hindle, D.; Fujita, K.; Mackey, K.

    2006-01-01

    Northeast Asia is a region of broad deformation resulting from the convergence of the Eurasian (EU) and North American (NA) plates. Part of this convergence has been suggested to be relieved by the extrusion and deformation of the Okhotsk plate (OK). Three models for the deformation of the seismically active northwestern corner of the Okhotsk plate, based on different modes of deformation partitioning, are calculated and compared to observations from GPS, seismicity, and geology. The results suggest that this region is being extruded southeastward and deforming internally by a mixture of pure contraction, ``smooth'' extrusion, and ``rigid'' extrusion. Calculated extrusion rates are ~3-5.5 mm/yr, comparable to estimates from geologic data, and internal deformation rates are ~3.0 × 10-9 yr -1. Internal deformation may be only partially accommodated by seismicity, but the short time span of seismic data leaves this subject to large uncertainty.

  17. FEM simulation of friction testing method based on combined forward rod-backward can extrusion

    DEFF Research Database (Denmark)

    Nakamura, T; Bay, Niels; Zhang, Z. L

    1997-01-01

    A new friction testing method by combined forward rod-backward can extrusion is proposed in order to evaluate frictional characteristics of lubricants in forging processes. By this method the friction coefficient mu and the friction factor m can be estimated along the container wall and the conical...... curves are obtained by rigid-plastic FEM simulations in a combined forward rod-backward can extrusion process for a reduction in area R-b = 25, 50 and 70 percent in the backward can extrusion. It is confirmed that the friction factor m(p) on the punch nose in the backward cart extrusion has almost...... in a mechanical press with aluminium alloy A6061 as the workpiece material and different kinds of lubricants. They confirm the analysis resulting in reasonable values for the friction coefficient and the friction factor....

  18. 76 FR 80887 - Antidumping Order on Aluminum Extrusions from the People's Republic of China: Initiation of...

    Science.gov (United States)

    2011-12-27

    ... frames, solar panels, curtain walls, or furniture. Such parts that otherwise meet the definition of..., and solar panels. The scope also excludes finished goods containing aluminum extrusions that are...

  19. 78 FR 66895 - Aluminum Extrusions From the People's Republic of China: Preliminary Results of Changed...

    Science.gov (United States)

    2013-11-07

    ... frames, solar panels, curtain walls, or furniture. Such parts that otherwise meet the definition of..., and solar panels. The scope also excludes finished goods containing aluminum extrusions that are...

  20. 77 FR 39683 - Aluminum Extrusions From the People's Republic of China: Preliminary Results of Changed...

    Science.gov (United States)

    2012-07-05

    ... frames, door frames, solar panels, curtain walls, or furniture. Such parts that otherwise meet the..., and solar panels. The scope also excludes finished goods containing aluminum extrusions that are...

  1. HotRegion: a database of predicted hot spot clusters.

    Science.gov (United States)

    Cukuroglu, Engin; Gursoy, Attila; Keskin, Ozlem

    2012-01-01

    Hot spots are energetically important residues at protein interfaces and they are not randomly distributed across the interface but rather clustered. These clustered hot spots form hot regions. Hot regions are important for the stability of protein complexes, as well as providing specificity to binding sites. We propose a database called HotRegion, which provides the hot region information of the interfaces by using predicted hot spot residues, and structural properties of these interface residues such as pair potentials of interface residues, accessible surface area (ASA) and relative ASA values of interface residues of both monomer and complex forms of proteins. Also, the 3D visualization of the interface and interactions among hot spot residues are provided. HotRegion is accessible at http://prism.ccbb.ku.edu.tr/hotregion.

  2. Preparation and Evaluation of Pellets Using Acacia and Tragacanth by Extrusion-Spheronization

    OpenAIRE

    S. Pirmoradi; M R. Abbaspour; A. Akhgari

    2011-01-01

    Background and the purpose of the study: Extrusion-spheronization is an established technique for the production of pellets for pharmaceutical applications. In this study, the feasibility and influence of the incorporation of acacia, by itself and in combination with tragacanth, on the ability of formulations containing 2 model of drugs (ibuprofen and theophylline) to form spherical pellets by extrusion-spheronization was investigated.Material and Methods: Formulations containing different ra...

  3. Inductive ingot heating for extrusion press applications; Induktive Bolzenerwaermung fuer Strangpressanwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Stefan [I.A.S. Induktions-Anlagen + Service GmbH und Co. KG, Iserlohn (Germany)

    2013-03-15

    Inductive heating of large-format aluminium ingots on modern extrusion press lines generates significant process-engineering benefits. In addition, the proportion of special alloys processed is continuously increasing, accompanied simultaneously by ever smaller production batches, both of which are factors necessitating improvement of and greater flexibility in process-cycle control. This report examines a system concept recently commissioned on one of the world's largest aluminium extrusion presses. (orig.)

  4. Magnetic susceptibility of semiconductor melts

    International Nuclear Information System (INIS)

    Kutvitskij, V.A.; Shurygin, P.M.

    1975-01-01

    The temperature dependences chi of various alloys confirm the existence of cluster formations in molten semiconductors, the stability of these formations in melts being considerably affected by the anion nature. The concentrational dependences of the magnetic susceptibility for all the investigated systems exhibit the diamagnetism maxima corresponding to the compound compositions. Heating the melt causes ''smearing'' the maxima, which is related with the cluster structure dissociation. The existence of the maxima concentrational dependence chi corresponding to BiTe and BiSe is found in the isotherms. The non-linear dependence of chi on the composition shows the absence of a single-valued relation between the phase diagram and the chi-diagram for melts

  5. Functionalization of LDPE and mLLDPE via grafting trans-ethylene-1,2-dicarboxylic acid by reactive extrusion

    Directory of Open Access Journals (Sweden)

    2010-03-01

    Full Text Available An investigation was made of grafting trans-ethylene-1,2-dicarboxylic acid (TEDA onto metallocene-linear low-density polyethylene (mLLDPE and low-density polyethylene (LDPE in the course of reactive extrusion. The initiator was 1,3-bis-(tert-butyl-peroxyisopropylbenzene. The graft efficiency of TEDA has been shown to increase with increasing initiator concentration, irrespective of polyethylene type. The graft values for LDPE were higher than for mLLDPE over the initiator concentration range (0.05 to 0.4 wt%. The rheological properties of mLLDPE were found to undergo more tangible changes during functionalization than those of LDPE. These changes were caused by side reactions, mainly macromolecular crosslinking. It has been established that some carboxyl groups get transformed to anhydride groups in the grafted product. The concentration of end double bonds reduces, but intramolecular unsaturation in both polyethylenes increases. Data are presented on thermal and stress-strain (mechanical properties of virgin and functionalized polymers, as well as rheological and viscoelastic properties of their melts.

  6. Suitability of the Yield Criterion in Numerical Simulation of Stretch Bending of Aluminum Extrusions

    International Nuclear Information System (INIS)

    Li, X.Q.; Zhou, X.B.; Wu, X.D.; Gao, H.Z.

    2005-01-01

    Stretch bending is commonly used to shape thin-walled extrusions in aerospace and automotive industries. The extrusions are pre-stretched and bent over rigid curved dies. Effective application of this process demands sufficient knowledge of how different parameters influence the final shape of the product. Numerical simulation is an effective approach to investigate these issues presently. However, the validity of simulation result depends strongly on a precise description of the mechanical behavior of the material. Due to crystallographic texture caused by the extrusion process, aluminium extrusions exhibit significant plastic anisotropy which need be described by advanced constitutive model. In this work stretch bending of aluminum extrusions is simulated by using different anisotropic criteria (Hill quadratic, Barlat three-parameter). The influence of two yield criteria on predicting maximum die force immediately before unloading, permanent sagging and vertical springback displacement in the middle section of extrusion are compared. Maximum die force and springback calculated by two yield criteria are found to be almost same. Permanent sagging is obviously underestimated by two yield criteria, however, prediction by Barlat three-parameter is closer to experiment than one of Hill quadratic yield criterion

  7. Shuttle Primary Reaction Control Subsystem Thruster Fuel Valve Pilot Seal Extrusion: A Failure Correlation

    Science.gov (United States)

    Waller, Jess; Saulsberry, Regor L.

    2003-01-01

    Pilot operated valves (POVs) are used to control the flow of hypergolic propellants monomethylhydrazine (fuel) and nitrogen tetroxide (oxidizer) to the Shuttle orbiter Primary Reaction Control Subsystem (PRCS) thrusters. The POV incorporates a two-stage design: a solenoid-actuated pilot stage, which in turn controls a pressure-actuated main stage. Isolation of propellant supply from the thruster chamber is accomplished in part by a captive polytetrafluoroethylene (PTFE) pilot seal retained inside a Custom 455.1 stainless steel cavity. Extrusion of the pilot seal restricts the flow of fuel around the pilot poppet, thus impeding or preventing the main valve stage from opening. It can also prevent the main stage from staying open with adequate force margin, particularly if there is gas in the main stage actuation cavity. During thruster operation on-orbit, fuel valve pilot seal extrusion is commonly indicated by low or erratic chamber pressure or failure of the thruster to fire upon command (Fail-Off). During ground turnaround, pilot seal extrusion is commonly indicated by slow gaseous nitrogen (GN2) main valve opening times (greater than 38 ms) or slow water main valve opening response times (greater than 33 ms). Poppet lift tests and visual inspection can also detect pilot seal extrusion during ground servicing; however, direct metrology on the pilot seat assembly provides the most quantitative and accurate means of identifying extrusion. Minimizing PRCS fuel valve pilot seal extrusion has become an important issue in the effort to improve PRCS reliability and reduce associated life cycle costs.

  8. On the rapid melt quenching

    International Nuclear Information System (INIS)

    Usatyuk, I.I.; Novokhatskij, I.A.; Kaverin, Yu.F.

    1994-01-01

    Specific features of instrumentation of traditionally employed method of melt spinning (rapid quenching), its disadvantages being discussed, were analyzed. The necessity of the method upgrading as applied to the problems of studying fine structure of molten metals and glasses was substantiated. The principle flowsheet of experimental facility for extremely rapid quenching of the melts of metals is described, specificity of its original functional units being considered. The sequence and character of all the principal stages of the method developed were discussed. 18 refs.; 3 figs

  9. Quality improvement of melt extruded laminar systems using mixture design.

    Science.gov (United States)

    Hasa, D; Perissutti, B; Campisi, B; Grassi, M; Grabnar, I; Golob, S; Mian, M; Voinovich, D

    2015-07-30

    This study investigates the application of melt extrusion for the development of an oral retard formulation with a precise drug release over time. Since adjusting the formulation appears to be of the utmost importance in achieving the desired drug release patterns, different formulations of laminar extrudates were prepared according to the principles of Experimental Design, using a design for mixtures to assess the influence of formulation composition on the in vitro drug release from the extrudates after 1h and after 8h. The effect of each component on the two response variables was also studied. Ternary mixtures of theophylline (model drug), monohydrate lactose and microcrystalline wax (as thermoplastic binder) were extruded in a lab scale vertical ram extruder in absence of solvents at a temperature below the melting point of the binder (so that the crystalline state of the drug could be maintained), through a rectangular die to obtain suitable laminar systems. Thanks to the desirability approach and a reliability study for ensuring the quality of the formulation, a very restricted optimal zone was defined within the experimental domain. Among the mixture components, the variation of microcrystalline wax content played the most significant role in overall influence on the in vitro drug release. The formulation theophylline:lactose:wax, 57:14:29 (by weight), selected based on the desirability zone, was subsequently used for in vivo studies. The plasma profile, obtained after oral administration of the laminar extruded system in hard gelatine capsules, revealed the typical trend of an oral retard formulation. The application of the mixture experimental design associated to a desirability function permitted to optimize the extruded system and to determine the composition space that ensures final product quality. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Thermal Stabilization study of polyacrylonitrile fiber obtained by extrusion

    Directory of Open Access Journals (Sweden)

    Robson Fleming Ribeiro

    2015-12-01

    Full Text Available A low cost and environmental friendly extrusion process of the Polyacrylonitrile (PAN polymer was viabilized by using the 1,2,3-propanetriol (glycerol as a plasticizer. The characterization of the fibers obtained by this process was the object of study in the present work. The PAN fibers were heat treated in the range of 200 °C to 300 °C, which is the temperature range related to the stabilization/oxidation step. This is a limiting phase during the carbon fiber processing. The characterization of the fibers was made using infrared spectroscopy, thermal analysis and microscopy. TGA revealed that the degradation of the extruded PAN co-VA fibers between 250 °C and 350 °C, corresponded to a 9% weight loss to samples analyzed under oxidizing atmosphere and 18% when the samples were analyzed under inert atmosphere. DSC showed that the exothermic reactions on the extruded PAN co-VA fibers under oxidizing synthetic air was broader and the cyclization started at a lower temperature compared under inert atmosphere. Furthermore, FT-IR analysis correlated with thermal anlysis showed that the stabilization/oxidation process of the extruded PAN fiber were coherent with other works that used PAN fibers obtained by other spinning processes.

  11. Utilization and Fortification of Patin Fish on Extrusion Snack

    Directory of Open Access Journals (Sweden)

    Mala Nurilmala

    2014-11-01

    Full Text Available Catfish (Pangasius sp. is a well cultured freshwater fish. Fortification improves protein level in snack and an effort to vary catfish fish product. The purpose of this study was to determine drying method for fish grit, formulation of snack and its properties. Grit formation by several drying methods and proximate (AOAC and degree of polarization. Snack used based on the physical measurement, namely development ratio. Formulations of grit composition of corn: rice: fish were 70%:30%:0% (K, 65%:25%:10% (A, 62.5%:22.5%:15% (B, 60%:20%:20% (C. Fish addition only effect the color of snack based on sensory analysis. There was no effect on snacks physical properties both 10% and 15% of fish grit added. Chemical measurements comprised water, ash, lipid, protein levels and polarization degree. Statistical analysis showed that fish addition effect the protein level on extrusion snack. In addition, polarization measurement showed that the snack with fish addition of 10% (A and 15%( B are fully gelatinized.Keyword: formulation, patin fish, snack

  12. Current advances and future perspectives in extrusion-based bioprinting.

    Science.gov (United States)

    Ozbolat, Ibrahim T; Hospodiuk, Monika

    2016-01-01

    Extrusion-based bioprinting (EBB) is a rapidly growing technology that has made substantial progress during the last decade. It has great versatility in printing various biologics, including cells, tissues, tissue constructs, organ modules and microfluidic devices, in applications from basic research and pharmaceutics to clinics. Despite the great benefits and flexibility in printing a wide range of bioinks, including tissue spheroids, tissue strands, cell pellets, decellularized matrix components, micro-carriers and cell-laden hydrogels, the technology currently faces several limitations and challenges. These include impediments to organ fabrication, the limited resolution of printed features, the need for advanced bioprinting solutions to transition the technology bench to bedside, the necessity of new bioink development for rapid, safe and sustainable delivery of cells in a biomimetically organized microenvironment, and regulatory concerns to transform the technology into a product. This paper, presenting a first-time comprehensive review of EBB, discusses the current advancements in EBB technology and highlights future directions to transform the technology to generate viable end products for tissue engineering and regenerative medicine. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Fluid Structure Interaction Techniques For Extrusion And Mixing Processes

    Science.gov (United States)

    Valette, Rudy; Vergnes, Bruno; Coupez, Thierry

    2007-05-01

    This work focuses on the development of numerical techniques devoted to the simulation of mixing processes of complex fluids such as twin-screw extrusion or batch mixing. In mixing process simulation, the absence of symmetry of the moving boundaries (the screws or the rotors) implies that their rigid body motion has to be taken into account by using a special treatment We therefore use a mesh immersion technique (MIT), which consists in using a P1+/P1-based (MINI-element) mixed finite element method for solving the velocity-pressure problem and then solving the problem in the whole barrel cavity by imposing a rigid motion (rotation) to nodes found located inside the so called immersed domain, each sub-domain (screw, rotor) being represented by a surface CAD mesh (or its mathematical equation in simple cases). The independent meshes are immersed into a unique background computational mesh by computing the distance function to their boundaries. Intersections of meshes are accounted for, allowing to compute a fill factor usable as for the VOF methodology. This technique, combined with the use of parallel computing, allows to compute the time-dependent flow of generalized Newtonian fluids including yield stress fluids in a complex system such as a twin screw extruder, including moving free surfaces, which are treated by a "level set" and Hamilton-Jacobi method.

  14. Application of Electrostatic Extrusion - Flavour Encapsulation and Controlled Release.

    Science.gov (United States)

    Manojlovic, Verica; Rajic, Nevenka; Djonlagic, Jasna; Obradovic, Bojana; Nedovic, Viktor; Bugarski, Branko

    2008-03-03

    The subject of this study was the development of flavour alginate formulationsaimed for thermally processed foods. Ethyl vanilline was used as the model flavourcompound. Electrostatic extrusion was applied for the encapsulation of ethyl vanilline inalginate gel microbeads. The obtained microbeads with approx. 10 % w/w of ethylvanilline encapsulated in about 2 % w/w alginate were uniformly sized spheres of about450 μm. Chemical characterization by H-NMR spectroscopy revealed that the alginateused in this study had a high content (67 %) of guluronic residues and was rich in GG diadblocks (FGG = 55%) and thus presented a high-quality immobilisation matrix. The thermalbehaviour of alginate beads encapsulating ethyl vanilline was investigated bythermogravimetric (TG) and differential scanning calorimetry measurements (TG-DSC)under heating conditions which mimicked usual food processing to provide informationabout thermal decomposition of alginate matrix and kinetics of aroma release. Two wellresolved weight losses were observed. The first one was in the 50-150 °C temperaturerange with the maximum at approx. 112 °C, corresponding to the dehydration of thepolymer network. The second loss in the 220-325 °C temperature range, with a maximumat ~ 247 °C corresponded to the release of vanilline. The obtained results indicate that up to230 °C most of the vanilline remained intacta, while prolonged heating at elevatedtemperatures led to the entire loss of the aroma compound.

  15. Application of Electrostatic Extrusion – Flavour Encapsulation and Controlled Release

    Science.gov (United States)

    Manojlovic, Verica; Rajic, Nevenka; Djonlagic, Jasna; Obradovic, Bojana; Nedovic, Viktor; Bugarski, Branko

    2008-01-01

    The subject of this study was the development of flavour alginate formulations aimed for thermally processed foods. Ethyl vanilline was used as the model flavour compound. Electrostatic extrusion was applied for the encapsulation of ethyl vanilline in alginate gel microbeads. The obtained microbeads with approx. 10 % w/w of ethyl vanilline encapsulated in about 2 % w/w alginate were uniformly sized spheres of about 450 μm. Chemical characterization by H-NMR spectroscopy revealed that the alginate used in this study had a high content (67 %) of guluronic residues and was rich in GG diad blocks (FGG = 55%) and thus presented a high-quality immobilisation matrix. The thermal behaviour of alginate beads encapsulating ethyl vanilline was investigated by thermogravimetric (TG) and differential scanning calorimetry measurements (TG-DSC) under heating conditions which mimicked usual food processing to provide information about thermal decomposition of alginate matrix and kinetics of aroma release. Two well resolved weight losses were observed. The first one was in the 50-150 °C temperature range with the maximum at approx. 112 °C, corresponding to the dehydration of the polymer network. The second loss in the 220-325 °C temperature range, with a maximum at ∼ 247 °C corresponded to the release of vanilline. The obtained results indicate that up to 230 °C most of the vanilline remained intacta, while prolonged heating at elevated temperatures led to the entire loss of the aroma compound. PMID:27879775

  16. Analysis of hot rolling and hot forging effects on mechanical properties and microstructure of ZrNbMoGe alloy

    International Nuclear Information System (INIS)

    AH Ismoyo; Parikin; Bandriyana

    2014-01-01

    Research on formation technique by a combined method of rolling and forging has been carried out in order to improve the mechanical properties of ZrNbMoGe alloy to be used as fuel cladding in NPP (Nuclear Power Plant) application. The effects of rolling and forging were analyzed several tests. The tests were conducted for zirconium alloy specimen with a composition of (in % wt.) 97% Zr, 0,5% Mo, 2% Nb and 0,5% Ge, where the specimen was melted with an arc-furnace. The hot rolling and forging were conducted at 900 °C and 950 °C respectively. Hardness test was carried out by using a microhardness testing machine, while microstructure examination and crystal structure analysis were conducted with an optical microscope and an X-ray diffractometer. The results show that the hardness of the alloy increase from 141.21 HV (starting material) to 210.47 HV (hot rolled material) and 365.75 HV (hot forged material). Texturing phenomenon is clearly figured on the microstructure due to hot rolling and forging process. Analysis by diffractogram also indicates that the hot rolling and forging process has influence on the crystal orientation of dominant preferred direction in the reflection plane of (10ī1), recorded from the rise of intensity counting from about 2500 to 3000. In summary, hot forging and rolling process can change the mechanical properties (hardness and texture) and microstructure of materials. (author)

  17. Pellets de trigo e soja produzidos por extrusão Wheat and soybean pellets produced by extrusion-cooking

    Directory of Open Access Journals (Sweden)

    Sin Huei Wang

    2008-09-01

    Full Text Available A mistura de trigo e soja representa uma importante fonte calórico-protéica com proteínas de boa qualidade. Apesar disso, a utilização da soja como ingrediente tem sido limitada pelo seu sabor de feijão cru (beany flavor, o qual é melhorado pelo processo de extrusão. Foram estudados os efeitos de umidade da mistura, Temperatura de Barril (TB e Velocidade de Rotação de Parafuso (VRP, Nº 5 do extrusor no Índice de Expansão (IE, no Índice de Solubilidade em Água (ISA e nas características sensoriais de pellets produzidos com mistura de trigo e soja (90:10, objetivando a otimização deste processo para a obtenção de pellets fritos com melhores qualidades sensoriais. A farinha mista crua foi extrusada em 2 umidades (32 e 35%, 4 TB (60 a 90 °C e 4 VRP (60 a 150 rpm, totalizando 32 tratamentos. O pellet frito, preparado com a farinha mista com 32% de umidade e extrusada em 60 rpm a 80 °C, apresentou o maior IE e as melhores qualidades sensoriais (aparência, sabor e textura, sendo preferido pela equipe de provadores não treinados, tanto com sabor de bacon como com sabor de queijo.The mixture of wheat with soybean represents an important calorie-protein source with good protein quality. In spite of this, the use of soybeans as an ingredient has been limited by their beany flavor, which is improved by the extrusion process. Effects of mixture moisture, Barrel Temperature (BT and Screw-Speed (SS, Nº 5 on Expansion Index (EI, Water Solubility Index (WSI and sensory characteristics of pellets produced with a wheat-soybean (90:10 mixture were studied, in order to optimize this process for obtaining fried pellets with better sensory qualities. Raw mixed flour was extruded at two moisture contents (32 and 35%, four BT (60 to 90 °C and four SS (60 to 150 rpm, totalizing 32 treatments. The fried pellets, prepared with the mixed flour with 32% moisture and extruded at 60 rpm and 80 °C, presented the greatest EI and the best sensory

  18. Melt water interaction tests. PREMIX tests PM10 and PM11

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, A.; Schuetz, W.; Will, H. [Forschungszentrum Karlsruhe Inst. fuer Reaktorsicherheit, Karlsruhe (Germany)

    1998-01-01

    A series of experiments is being performed in the PREMIX test facility in which the mixing behaviour is investigated of a hot alumina melt discharged into water. The major parameters have been: the melt mass, the number of nozzles, the distance between the nozzle and the water, and the depth of the water. The paper describes the last two tests in which 20 kg of melt were released through one and three nozzles, respectively, directly into the water whose depth was 500 mm. The melt penetration and the associated phenomena of mixing are described by means of high-speed films and various measurements. The steam production and, subsequently, the pressure increased markedly only after the melt had reached the bottom of the pool. Spreading of the melt across the bottom caused violent boiling in both tests. Whereas the boiling lasted for minutes in the single-jet test, a steam explosion occurred in the triple-jet test about one second after the start of melt penetration. (author)

  19. Multifragmentation of hot nuclei

    International Nuclear Information System (INIS)

    Tamain, B.

    1990-10-01

    It is difficult to deposit a large amount (∼ 1 Gev) of excitation energy into a nucleus. And if one wants to deposit large excitation energy values, the best way consists of shooting a given target nucleus with several nucleons, which can be achieved by using intermediate energy (10-100 MeV/nucleon) heavy ions. Such very excited objects were named hot nuclei. The study of hot nuclei has been undertaken only for 7 years because intermediate energy heavy ion facilities were not available before. The game is then to determine the decay properties of such nuclei, their limits of existence. Their study is connected with general properties of nuclear matter: namely its equation of state. Of special interest, is the onset of a new decay mechanism: multifragmentation, which is the non-sequential disassembly of a hot nucleus into several light nuclei (often called intermediate-mass fragments or IMF) or particles. This paper, shows how this mechanism can reflect fundamental properties of nuclear matter, but also how its experimental signature is difficult to establish. Multifragmentation has also been studied by using very energetic projectiles (protons and heavy ions) in the relativistic or ultra-relativistic region. The multifragmentation question of hot nuclei is far from being solved. One knows that IMF production increases when the excitation energy brought into a system is strongly increased, but very little is known about the mechanisms involved and a clear onset for multifragmentation is not established

  20. Utilizing hot electrons

    Energy Technology Data Exchange (ETDEWEB)

    Nozik, Arthur J.

    2018-03-01

    In current solar cells, any photon energy exceeding the semiconductor bandgap is lost before being collected, limiting the cell performance. Hot carrier solar cells could avoid these losses. Now, a detailed experimental study and analysis shows that this strategy could lead to an improvement of the photoconversion efficiency in practice.

  1. Mechanical shielded hot cell

    International Nuclear Information System (INIS)

    Higgy, H.R.; Abdel-Rassoul, A.A.

    1983-01-01

    A plan to erect a mechanical shielded hot cell in the process hall of the Radiochemical Laboratory at Inchas is described. The hot cell is designed for safe handling of spent fuel bundles, from the Inchas reactor, and for dismantling and cutting the fuel rods in preparation for subsequent treatment. The biological shielding allows for the safe handling of a total radioactivity level up to 10,000 MeV-Ci. The hot cell consists of an α-tight stainless-steel box, connected to a γ-shielded SAS, through an air-lock containing a movable carriage. The α-box is tightly connected with six dry-storage cavities for adequate storage of the spent fuel bundles. Both the α-box, with the dry-storage cavities, and the SAS are surrounded by 200-mm thick biological lead shielding. The α-box is equipped with two master-slave manipulators, a lead-glass window, a monorail crane and Padirac and Minirag systems. The SAS is equipped with a lead-glass window, tong manipulator, a shielded pit and a mechanism for the entry of the spent fuel bundle. The hot cell is served by adequate ventilation and monitoring systems. (author)

  2. Fractionation, ascent, and extrusion of magma at the Santiaguito volcanic dome, Guatemala

    Science.gov (United States)

    Scott, J.; Mather, T. A.; Pyle, D. M.

    2011-12-01

    The silicic dome complex of Santiaguito, Guatemala has exhibited continuous low-level activity for nearly 90 years[1]. Despite its longevity, remarkably little is known about the magmatic plumbing system beneath Santiaguito. We present preliminary constraints on this system, based on petrological analyses of lava samples. Amphibole thermobarometry suggests magma evolves during slow ascent through a phenocryst fractionation zone - a complex of dikes and sills, extending from at least ~24 km to at most ~12 km beneath Santiaguito. Discontinuous plagioclase size distributions suggest this slow fractionation ends at depth, and degassing-induced crystallization of microlites begins. The texture and geochemistry of microlites is consistent with uninterrupted final ascent; there is no evidence of shallow magma storage beneath Santiaguito. The normative composition of matrix glass, and the morphology and volume of plagioclase microlites suggests ascending magma crosses the rigidification threshold within preserved, and ductile behaviour is replaced by dominantly brittle behaviour, previously referred to as "final melt quench". We suggest rigidification slows the ascent of magma and may create the conduit plug previously observed at Santiaguito[2]. This rigid mass of magma may begin to fracture almost immediately to form a semi-permeable plug, before extruding onto the surface as blocky lava. The extrusion rate may be reflected in the extent of matrix glass decomposition to crystalline silica and alkali feldspar. This preliminary picture of the plumbing system beneath Santiaguito may lead to a greater understanding of the behaviour of this enigmatic volcano, and of the danger it poses to the region. However, our findings raise many further questions about the dynamics within silicic dome-forming systems that need to be addressed if we are to work towards a broad and more universal understanding of similar systems worldwide and the hazards they represent. [1] Rose, W.I., 1972

  3. Relationship Between Preoperative Extrusion of the Medial Meniscus and Surgical Outcomes After Partial Meniscectomy.

    Science.gov (United States)

    Kim, Sung-Jae; Choi, Chong Hyuk; Chun, Yong-Min; Kim, Sung-Hwan; Lee, Su-Keon; Jang, Jinyoung; Jeong, Howon; Jung, Min

    2017-07-01

    No previous study has examined arthritic change after meniscectomy with regard to extrusion of the medial meniscus. (1) To determine the factors related to preoperative meniscal extrusion; (2) to investigate the relationship between medial meniscal extrusion and postoperative outcomes of partial meniscectomy, and to identify a cutoff point of meniscal extrusion that contributes to arthritic change after partial meniscectomy in nonosteoarthritic knees. Cohort study; Level of evidence, 3. A total of 208 patients who underwent partial meniscectomy of the medial meniscus between January 2000 and September 2006 were retrospectively reviewed. The extent of extrusion and severity of degeneration of the medial meniscus as shown on preoperative MRI were evaluated. The minimum follow-up duration was 7 years. Clinical function was assessed with the Lysholm knee scoring scale, the International Knee Documentation Committee (IKDC) subjective knee evaluation form, and the Tapper and Hoover grading system. Radiological evaluation was conducted by use of the IKDC radiographic assessment scale. Regression analysis was performed to identify factors affecting preoperative extrusion of the medial meniscus and factors influencing follow-up results after partial meniscectomy. Receiver operating characteristic curve was used to identify a cutoff point for the extent of meniscal extrusion that was associated with arthritic change. The mean ± SD preoperative Lysholm knee score was 65.0 ± 6.3 and the mean IKDC subjective score was 60.1 ± 7.5. The mean follow-up functional scores were 93.2 ± 5.1 ( P meniscus showed a tendency to increase as the extent of intrameniscal degeneration increased, and the medial meniscus was extruded more in patients with horizontal, horizontal flap, and complex tears. The preoperative extent of meniscal extrusion had a statistically significant correlation with follow-up Lysholm knee score (coefficient = -0.10, P = .002), IKDC subjective score (coefficient

  4. Acoustic detection of melt particles

    International Nuclear Information System (INIS)

    Costley, R.D. Jr.

    1988-01-01

    The Reactor Safety Research Department at Sandia National Laboratories is investigating a type of Loss of Coolant Accident (LOCA). In this particular type of accident, core meltdown occurs while the pressure within the reactor pressure vessel (RPV) is high. If one of the instrument tube penetrations in the lower head fails, melt particles stream through the cavity and into the containment vessel. This experiment, which simulates this type accident, was performed in the Surtsev Direct Heating Test Facility which is approximately a 1:10 linear scaling of a large dry containment volume. A 1:10 linear scale model of the reactor cavity was placed near the bottom of the Surtsey vessel so that the exit of the cavity was at the vertical centerline of the vessel. A pressure vessel used to create the simulated molten core debris was located at the scaled height of the RPV. In order to better understand how the melt leaves the cavity and streams into the containment an array of five acoustic sensors was placed directly in the path of the melt particles about 30 feet from the exit of the sealed cavity. Highly damped, broadband sensors were chosen to minimize ringing so that individual particle hits could be detected. The goal was to count the signals produced by the individual particle hits to get some idea of how the melt particles left the cavity. This document presents some of the results of the experiment. 9 figs

  5. Thermodynamics of freezing and melting

    DEFF Research Database (Denmark)

    Pedersen, Ulf Rørbæk; Costigliola, Lorenzo; Bailey, Nicholas

    2016-01-01

    phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio...

  6. Development by extrusion of soyabari snack sticks: a nutritionally improved soya-maize product based on the Nigerian snack (kokoro).

    Science.gov (United States)

    Omueti, O; Morton, I D

    1996-01-01

    A nutritionally improved local snack compared to existing kokoro has been developed by extrusion cooking of different formulations of maize, soybean and condiments such as pepper, onion, salt, palm oil, plantain and banana. The improved snack was named as the 'soyabari snack stick'. The chemical composition of representative extruded products indicates a high level of crude protein, fat, energy, available lysine and improved in vitro digestibility compared to the usual maize-based products. The level of stachyose and raffinose were greatly reduced in the extruded products compared to raw soya. Formulations using various additives yielded products suitable for different consumers' preferences such as hot, sweet, bland, gritty or crispy and acceptable to taste assessors. Soyabari snack sticks were equally acceptable as Bombay mix, a product on the market in London. Sensory analysis showed no significant differences in the two products but the crude fibre content of Bombay mix was higher while the protein was slightly lower than for soyabari sticks. Local ingredients can produce acceptable extrudates.

  7. Hot Deformation Behavior of Hot-Extruded AA7175 Through Hot Torsion Tests.

    Science.gov (United States)

    Lee, Se-Yeon; Jung, Taek-Kyun; Son, Hyeon-Woo; Kim, Sang-Wook; Son, Kwang-Tae; Choi, Ho-Joon; Oh, Sang-Ho; Lee, Ji-Woon; Hyun, Soong-Keun

    2018-03-01

    The hot deformation behavior of hot-extruded AA7175 was investigated with flow curves and processing maps through hot torsion tests. The flow curves and the deformed microstructures revealed that dynamic recrystallization (DRX) occurred in the hot-extruded AA7175 during hot working. The failure strain was highest at medium temperature. This was mainly influenced by the dynamic precipitation of fine rod-shaped MgZn2. The processing map determined the optimal deformation condition for the alloy during hot working.

  8. Effects of Melt Processing on Evolution of Structure in PEEK

    Science.gov (United States)

    Georgiev, Georgi; Dai, Patrick Shuanghua; Oyebode, Elizabeth; Cebe, Peggy; Capel, Malcolm

    1999-01-01

    treatment scheme involving annealing/crystallization at T(sub a1) followed by annealing at T(sub a2) where either T(sub a1) T(sub a2). We proposed a model to explain multiple melting endotherms in PPS, treated according to one or two-stage melt or cold crystallization. Key features of this model are that multiple endotherms: (1) are due to reorganization/recrystallization after cold crystallization; and, (2) are dominated by crystal morphology after melt crystallization at high T. In other words, multiple distinct crystal populations are formed by the latter treatment, leading to observation of multiple melting. PEEK 45OG pellets (ICI Americas) were the starting material for this study. Films were compression molded at 400 C, then quenched to ice water. Samples were heated to 375 C in a Mettler FP80 hot stage and held for three min. to erase crystal seeds before cooling them to T(sub a1) = 280 C . Samples were held at T(sub a2) for a period of time, then immediately heated to 360 C. In the second treatment samples were held at T(sub a1) = 31 C for different crystallization times t(sub c) then cooled to 295 C and held 15 min. In situ (SAXS) experiments were performed at the Brookhaven National Synchrotron Light Source with the sample located inside the Mettler hot stage. The system was equipped with a two-dimensional position sensitive detector. The sample to detector distance was 172.7 cm and the X-ray wavelength was 1.54 Angstroms. SAXS data were taken continuously during the isothermal periods and during the heating to 360 C at 5 C/min. Each SAXS scan was collected for 30 sec. Since the samples were isotropic, circular integration was used to increase the signal to noise ratio. After dual stage melt crystallization with T(sub a1) T(sub a2), the amount of space remaining for additional growth at T(sub a2) depends upon the holding time at T(sub a1). The long period of crystals formed at T(sub a2) is smaller than that formed at T(sub a1) due to growth in a now

  9. Software Simulation of Hot Tearing

    DEFF Research Database (Denmark)

    Andersen, S.; Hansen, P.N.; Hattel, Jesper Henri

    1999-01-01

    The brittleness of a solidifying alloy in a temperature range near the solidus temperature has been recognised since the fifties as the mechanism responsible for hot tearing. Due to this brittlenes, the metal will crack under even small amounts of strain in that temperature range. We see these hot...... tears in castings close to hot centres, where the level of strain is often too high.Although the hot tearing mechanism is well understood, until now it has been difficult to do much to reduce the hot tearing tendency in a casting. In the seventies, good hot tearing criteria were developed by considering...... the solidification rate and the strain rate of the hot tear prone areas. But, until recently it was only possible to simulate the solidification rate, so that the criteria could not be used effectively.Today, with new software developments, it is possible to also simulate the strain rate in the hot tear prone areas...

  10. Hot Fuel Examination Facility (HFEF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Hot Fuel Examination Facility (HFEF) is one of the largest hot cells dedicated to radioactive materials research at Idaho National Laboratory (INL). The nation's...

  11. Metal extrusion using hydrostatic pressures; Le filage des metaux sous pression hydrostatique

    Energy Technology Data Exchange (ETDEWEB)

    Sauve, Ch [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The main problems connected with the deformation of metals due to extrusion are described. A method is put forward for calculating the rational rate of percentage deformation in the case of bar extrusion using a cylindrical container; reference is made to previous work on extrusion using a hydrostatic pressure with or without back-pressure. An extrusion process is described using hydrostatic pressure, without back-pressure, and using the lubricant for transmitting the thrust. This process has been used for eight years by the C.E.A. for the extrusion of a very wide range of metals, from beryllium to uranium and including steels; it leads to excellent surface textures. A very fine crystallization can be obtained on extruded products when the rate of extrusion is very low. There appears to be nothing against the use of high extrusion rates using this method. (author) [French] On expose les problemes generaux lies a la deformation des metaux par filage. On propose un calcul de la vitesse rationnelle de deformation pour cent dans le cas du filage de barres a partir d'un conteneur cylindrique, et l'on cite les travaux anterieurs sur le filage par faction d'une pression hydrostatique sans ou avec une contre-pression. On decrit un procede de filage par l'action d'une pression hydrostatique, sans contre-pression, utilisant le lubrifiant pour transmettre la poussee. Ce procede employe depuis 8 ans au C.E.A. pour filer les metaux les plus divers, depuis le beryllium jusqu'a l'uranium en passant par les aciers, permet d'obtenir d'excellents etats de surface. Une cristallisation tres fine peut etre obtenue sur les produits files lorsque le filage est tres lent. Rien ne parait s'opposer a ce que des filages rapides soient effectues avec cette methode. (auteur)

  12. Illustration of cross flow of polystyrene melts through a coathanger die

    Science.gov (United States)

    Schöppner, V.; Henke, B.

    2015-05-01

    To design an optimal coathanger die with a uniform flow rate distribution and low pressure drop, it is essential to understand the flow conditions in the die. This is important because the quality of the product is influenced by the flow velocity and the flow rate distribution. In extrusion dies, cross flows also occur in addition to the main flow, which flow perpendicular to the main flow. This results in pressure gradients in the extrusion direction, which have an influence on flow distribution and pressure drop in the die. In recent decades, quantitative representation and analysis of physical flow processes have made considerable progress in predicting the weather, developing drive technologies and designing aircraft using simulation methods and lab trials. Using the flow-line method, the flow is analyzed in flat film extrusion dies with a rectangular cross-section, in particular cross flows. The simplest method to visualize the flow is based on the measurement of obstacle orientation in the flow field by adding individual particles. A near-surface flow field can be visualized by using wool or textile yarns. By sticking thin, frayed at the ends of strands of wool surface that is to be examined cross flows, near-wall profiles of the flow and vortex and separation regions can be visualized. A further possibility is to add glass fibers and analyze the fiber orientation by microscopy and x-ray analysis. In this paper the influence of process parameters (e.g. melt temperatures and throughput) on cross flow and fiber orientation is described.

  13. Petrological systematics of mid-ocean ridge basalts: Constraints on melt generation beneath ocean ridges

    Science.gov (United States)

    Langmuir, Charles H.; Klein, Emily M.; Plank, Terry

    Mid-ocean ridge basalts (MORB) are a consequence of pressure-release melting beneath ocean ridges, and contain much information concerning melt formation, melt migration and heterogeneity within the upper mantle. MORB major element chemical systematics can be divided into global and local aspects, once they have been corrected for low pressure fractionation and interlaboratory biases. Regional average compositions for ridges unaffected by hot spots ("normal" ridges) can be used to define the global correlations among normalized Na2O, FeO, TiO2 and SiO2 contents, CaO/Al2O3 ratios, axial depth and crustal thickness. Back-arc basins show similar correlations, but are offset to lower FeO and TiO2 contents. Some hot spots, such as the Azores and Galapagos, disrupt the systematics of nearby ridges and have the opposite relationships between FeO, Na2O and depth over distances of 1000 km. Local variations in basalt chemistry from slow- and fast-spreading ridges are distinct from one another. On slow-spreading ridges, correlations among the elements cross the global vector of variability at a high angle. On the fast-spreading East Pacific Rise (EPR), correlations among the elements are distinct from both global and slow-spreading compositional vectors, and involve two components of variation. Spreading rate does not control the global correlations, but influences the standard deviations of axial depth, crustal thickness, and MgO contents of basalts. Global correlations are not found in very incompatible trace elements, even for samples far from hot spots. Moderately compatible trace elements for normal ridges, however, correlate with the major elements. Trace element systematics are significantly different for the EPR and the mid-Atlantic Ridge (MAR). Normal portions of the MAR are very depleted in REE, with little variability; hot spots cause large long wavelength variations in REE abundances. Normal EPR basalts are significantly more enriched than MAR basalts from normal

  14. Terahertz inline wall thickness monitoring system for plastic pipe extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Hauck, J., E-mail: j.hauck@skz.de, E-mail: d.stich@skz.de, E-mail: p.heidemeyer@skz.de, E-mail: m.bastian@skz.de, E-mail: t.hochrein@skz.de; Stich, D., E-mail: j.hauck@skz.de, E-mail: d.stich@skz.de, E-mail: p.heidemeyer@skz.de, E-mail: m.bastian@skz.de, E-mail: t.hochrein@skz.de; Heidemeyer, P., E-mail: j.hauck@skz.de, E-mail: d.stich@skz.de, E-mail: p.heidemeyer@skz.de, E-mail: m.bastian@skz.de, E-mail: t.hochrein@skz.de; Bastian, M., E-mail: j.hauck@skz.de, E-mail: d.stich@skz.de, E-mail: p.heidemeyer@skz.de, E-mail: m.bastian@skz.de, E-mail: t.hochrein@skz.de; Hochrein, T., E-mail: j.hauck@skz.de, E-mail: d.stich@skz.de, E-mail: p.heidemeyer@skz.de, E-mail: m.bastian@skz.de, E-mail: t.hochrein@skz.de [SKZ - German Plastics Center, Wuerzburg (Germany)

    2014-05-15

    Conventional and commercially available inline wall thickness monitoring systems for pipe extrusion are usually based on ultrasonic or x-ray technology. Disadvantages of ultrasonic systems are the usual need of water as a coupling media and the high damping in thick walled or foamed pipes. For x-ray systems special safety requirements have to be taken into account because of the ionizing radiation. The terahertz (THz) technology offers a novel approach to solve these problems. THz waves have many properties which are suitable for the non-destructive testing of plastics. The absorption of electrical isolators is typically very low and the radiation is non-ionizing in comparison to x-rays. Through the electromagnetic origin of the THz waves they can be used for contact free measurements. Foams show a much lower absorption in contrast to acoustic waves. The developed system uses THz pulses which are generated by stimulating photoconductive switches with femtosecond laser pulses. The time of flight of THz pulses can be determined with a resolution in the magnitude of several ten femtoseconds. Hence the thickness of an object like plastic pipes can be determined with a high accuracy by measuring the time delay between two reflections on materials interfaces e.g. at the pipe's inner and outer surface, similar to the ultrasonic technique. Knowing the refractive index of the sample the absolute layer thickness from the transit time difference can be calculated easily. This method in principle also allows the measurement of multilayer systems and the characterization of foamed pipes.

  15. On high-pressure melting of tantalum

    Science.gov (United States)

    Luo, Sheng-Nian; Swift, Damian C.

    2007-01-01

    The issues related to high-pressure melting of Ta are discussed within the context of diamond-anvil cell (DAC) and shock wave experiments, theoretical calculations and common melting models. The discrepancies between the extrapolations of the DAC melting curve and the melting point inferred from shock wave experiments, cannot be reconciled either by superheating or solid-solid phase transition. The failure to reproduce low-pressure DAC melting curve by melting models such as dislocation-mediated melting and the Lindemann law, and molecular dynamics and quantum mechanics-based calculations, undermines their predictions at moderate and high pressures. Despite claims to the contrary, the melting curve of Ta (as well as Mo and W) remains inconclusive at high pressures.

  16. Cellulose Nanocomposites by Melt Compounding of TEMPO-Treated Wood Fibers in Thermoplastic Starch Matrix

    Directory of Open Access Journals (Sweden)

    Aline Cobut

    2014-04-01

    Full Text Available To facilitate melt compounding of cellulose nanofibrils (CNF based composites, wood pulp fibers were subjected to a chemical treatment whereby the fibers were oxidized using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO. This treatment introduced negatively charged carboxylate groups to the fibers. TEMPO-treated fibers (TempoF were added to a mixture of amylopectin starch, glycerol, and water. Granules were prepared from this mixture and processed into CNF composites by extrusion. TempoF were easier to process into composites as compared with non-treated pulp fibers (PF. SEM revealed partial disintegration of TempoF during melt processing. Consequently, TempoF gave composites with much better mechanical properties than those of conventional composites prepared from pulp fibers and TPS. Particularly, at 20 wt% TempoF content in the composite, the modulus and strength were much improved. Such a continuous melt processing route, as an alternative to laboratory solvent casting techniques, may promote large-scale production of CNF-based composites as an environmentally friendly alternative to synthetic plastics/composites.

  17. Hot subluminous star: HDE 283048

    International Nuclear Information System (INIS)

    Laget, M.; Vuillemin, A.; Parsons, S.B.; Henize, K.G.; Wray, J.D.

    1978-01-01

    The star HDE 283048, located at α = 3/sup h/50/sup m/.3, delta = +25 0 36', shows a strong ultraviolet continuum. Ground-based observations indicate a hot-dominated composite spectrum. Several lines of evidence suggest that the hot component is a hot subdwarf. 2 figures

  18. The Melting Behavior and Thermal Stability of Green Poly(L-lactic acid) with N, N, N, N'-Tetra(benzoyl) Ethylene Diamine Tetraacetic Acid Dihydrazide

    International Nuclear Information System (INIS)

    Cai, Y.; Qiang Xu, Q.; Ren, L.; Zhao, L.

    2015-01-01

    The thermal properties of green poly(L-lactic acid) (PLLA) with N, N, N, N'-tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide (NA) at different conditions were investigated. The melting behavior of PLLA/NA sample after isothermal crystallization at 100 degree C showed that the low-temperature melting peak shifted to high temperature with increasing of crystallization time. However, the high-temperature melting peak did not show any change. Meantime, the melting enthalpy of cold crystallization was higher than that of hot crystallization, and the difference between cold crystallization and hot crystallization increased from 0.31 J/g to 0.89 J/g with increasing of crystallization time. Heating or cooling rate affected the melting behavior of PLLA, the low-temperature and high-temperature melting peak shifted to low temperature with increasing of rate, and the ratio of melting peak area between low-temperature melting peak and high-temperature melting peak decreased. Thermal stability of PLLA/NA indicated that PLLA/NA only exhibited one decomposition stage as decomposition of PLLA. (author)

  19. Phenomenological Studies on Melt-Structure-Water Interactions (MSWI) during Postulated Severe Accidents

    International Nuclear Information System (INIS)

    Sehgal, B.R.; Park, H.S.; Giri, A.; Karbojian, A.; Jasiulevicius, A.; Hansson, R.C.; Chikkanagoudar, U.; Shiferaw, D.; Stepanyan, A.

    2004-01-01

    pressure generation and associated melt fragmentation. Approximately 70% of a melt drop was fragmented until the second bubble collapses during the steam explosion process. The quenching experiments employing a hot sphere, which dropped into coolant were performed to investigate the thermal behavior, e.g., direct contact boiling heat transfer, film boiling heat transfer etc., of the melt droplet prior to the triggering of steam explosion and consequently to provide the database to develop a theoretical model for the quenching boiling heat transfer. The POMECO experiments revealed the significant additional cooling capability in the debris bed when the control rod guide tubes were used to inject cooling water, showing the enhancement of the dryout heat flux and quenching rates. The COMECO tests showed that the presence of downcomers enhanced the quenching of the molten pool, decreasing the solidification time. Between the top and bottom addition of water, the bottom cooling dominates the cooling process. In the case of cooling with no downcomer, a strong effect of the injected gas velocity on the quenching (solidification) process was obtained. The effect of the downcomer was not as significant as that indicated in the POMECO tests. The SIMECO experiments were restarted to investigate the melt pool convection in multi-layer configuration which has metallic melt layers on the top and bottom and oxidic melt layer in the middle of the melt pool. The experimental results were compared to those from the previous SIMECO experiments with the uniform and two/layer melt pool configuration. The FOREVER-EC6 test in which water was injected on the top of the melt pool during the vessel creep was analyzed to investigate the important heat transfer parameters using the RELAP code. The analysis showed that the melt top and surface heat flux decreases with time due to the crust formation and that it is not possible to quench the melt pool with water flooding from top

  20. On melting of boron phosphide under pressure

    OpenAIRE

    Solozhenko, Vladimir; Mukhanov, V. A.

    2015-01-01

    Melting of cubic boron phosphide, BP, has been studied at pressures to 9 GPa using synchrotron X-ray diffraction and electrical resistivity measurements. It has been found that above 2.6 GPa BP melts congruently, and the melting curve exhibits negative slope (–60 ± 7 K/GPa), which is indicative of a higher density of the melt as compared to the solid phase.